diff --git a/components/upload-modal.html b/components/upload-modal.html
index a22e1bc3..1e7cb32d 100644
--- a/components/upload-modal.html
+++ b/components/upload-modal.html
@@ -209,12 +209,12 @@
                  <div class="space-y-2">
                     <label for="input-url" class="block text-sm font-medium text-text">Video URL</label>
                     <input id="input-url" type="url" class="input" placeholder="https://example.com/video.mp4" />
-                    <p class="text-xs text-muted">Direct link to a hosted video file.</p>
+                    <p class="text-xs text-muted">Primary hosted video source (URL-first playback).</p>
                 </div>
                  <div class="space-y-2">
                     <label for="input-magnet" class="block text-sm font-medium text-text">Magnet Link</label>
                     <input id="input-magnet" type="text" class="input" placeholder="magnet:?xt=urn:btih:..." />
-                    <p class="text-xs text-muted">Optional P2P fallback or primary source.</p>
+                    <p class="text-xs text-muted">Optional WebTorrent fallback when the URL is unavailable.</p>
                 </div>
             </div>
 
diff --git a/js/services/r2Service.js b/js/services/r2Service.js
index 3055297f..5c289192 100644
--- a/js/services/r2Service.js
+++ b/js/services/r2Service.js
@@ -31,6 +31,15 @@ import {
 } from "./videoNotePayload.js";
 
 const STATUS_VARIANTS = new Set(["info", "success", "error", "warning"]);
+const INFO_HASH_PATTERN = /^[a-f0-9]{40}$/;
+
+function normalizeInfoHash(value) {
+  return typeof value === "string" ? value.trim().toLowerCase() : "";
+}
+
+function isValidInfoHash(value) {
+  return INFO_HASH_PATTERN.test(value);
+}
 
 function createDefaultSettings() {
   return {
@@ -187,10 +196,10 @@ class R2Service {
       primaryVariant.m = mimeType;
     }
 
-    const normalizedHash =
-      typeof infoHash === "string" ? infoHash.trim().toLowerCase() : "";
+    const normalizedHash = normalizeInfoHash(infoHash);
     if (
       normalizedHash &&
+      isValidInfoHash(normalizedHash) &&
       (!primaryVariant.x || !String(primaryVariant.x).trim())
     ) {
       primaryVariant.x = normalizedHash;
@@ -705,14 +714,27 @@ class R2Service {
       } else {
         // Construct the Magnet Link
         // magnet:?xt=urn:btih:<infoHash>&dn=<filename>&ws=<publicUrl>
+        const normalizedInfoHash = normalizeInfoHash(infoHash);
+        const hasValidInfoHash = isValidInfoHash(normalizedInfoHash);
         let generatedMagnet = "";
         let generatedWs = "";
 
-        if (infoHash) {
-             const encodedDn = encodeURIComponent(file.name);
-             const encodedWs = encodeURIComponent(publicUrl);
-             generatedMagnet = `magnet:?xt=urn:btih:${infoHash}&dn=${encodedDn}&ws=${encodedWs}`;
-             generatedWs = publicUrl;
+        if (hasValidInfoHash) {
+          const encodedDn = encodeURIComponent(file.name);
+          const encodedWs = encodeURIComponent(publicUrl);
+          generatedMagnet = `magnet:?xt=urn:btih:${normalizedInfoHash}&dn=${encodedDn}&ws=${encodedWs}`;
+          generatedWs = publicUrl;
+        } else {
+          if (infoHash) {
+            userLogger.warn(
+              "Invalid info hash provided. Skipping magnet and webseed generation.",
+              infoHash
+            );
+          }
+          this.setCloudflareUploadStatus(
+            "Info hash missing or invalid. Publishing URL-first without WebTorrent fallback.",
+            "warning"
+          );
         }
 
         const rawVideoPayload = {
@@ -731,7 +753,7 @@ class R2Service {
         const mergedNip71 = this.buildNip71MetadataForUpload(metadata?.nip71, {
           publicUrl,
           file,
-          infoHash,
+          infoHash: hasValidInfoHash ? normalizedInfoHash : "",
         });
         if (mergedNip71 && Object.keys(mergedNip71).length) {
           rawVideoPayload.nip71 = mergedNip71;
diff --git a/js/ui/components/UploadModal.js b/js/ui/components/UploadModal.js
index 642553ae..06c0d0cf 100644
--- a/js/ui/components/UploadModal.js
+++ b/js/ui/components/UploadModal.js
@@ -10,6 +10,16 @@ import {
 import { createTorrentMetadata } from "../../utils/torrentHash.js";
 import { sanitizeBucketName } from "../../storage/r2-mgmt.js";
 
+const INFO_HASH_PATTERN = /^[a-f0-9]{40}$/;
+
+function normalizeInfoHash(value) {
+  return typeof value === "string" ? value.trim().toLowerCase() : "";
+}
+
+function isValidInfoHash(value) {
+  return INFO_HASH_PATTERN.test(value);
+}
+
 export class UploadModal {
   constructor({
     authService,
@@ -671,6 +681,29 @@ export class UploadModal {
           userLogger.warn("Failed to calculate info hash:", hashErr);
       }
 
+      const normalizedInfoHash = normalizeInfoHash(infoHash);
+      const hasValidInfoHash = isValidInfoHash(normalizedInfoHash);
+
+      if (!hasValidInfoHash) {
+          const proceed = confirm(
+            "We couldn't calculate a valid info hash. Publishing will continue with URL-first playback only, and WebTorrent fallback will be unavailable. Continue?"
+          );
+          if (!proceed) {
+              this.updateUploadStatus(
+                "Upload canceled. A valid info hash is required for WebTorrent fallback.",
+                "warning"
+              );
+              this.isUploading = false;
+              this.submitButton.disabled = false;
+              this.updateProgress(null);
+              return;
+          }
+          this.updateUploadStatus(
+            "Continuing without WebTorrent fallback (info hash unavailable).",
+            "warning"
+          );
+      }
+
       // 2. Upload
       await this.r2Service.uploadVideo({
           npub,
@@ -678,7 +711,7 @@ export class UploadModal {
           thumbnailFile,
           torrentFile,
           metadata,
-          infoHash,
+          infoHash: hasValidInfoHash ? normalizedInfoHash : "",
           settingsInput: this.collectSettingsForm(),
           publishVideoNote: this.publishVideoNote,
           onReset: () => this.resetForm(),