Video downloader fails or produces broken files on Instagram and Facebook (likely all MSE-based site

I'm running into a consistent problem with the video download tool in Parallels Toolbox on both Instagram and Facebook.

Issue 1 -- The tool fails outright on post URLs from these sites. Pasting a standard Instagram or Facebook post/video link returns "Failed to get the video / this video service may not be supported." Both platforms (like TikTok, YouTube, and most modern video sites) load video through the Media Source Extensions (MSE) API rather than a plain <video src="...">. That means the visible video element only ever exposes a blob: URL -- not a real, fetchable one. Any tool that reads video.src or video.currentSrc directly from the page will fail on all of these sites, not just Instagram. To support them, the tool needs to inspect the actual network requests the page makes (or use a headless browser / Chrome DevTools Protocol network listener) to find the real CDN media URLs, rather than relying on the DOM's video element.

Issue 2 -- Even with a direct CDN URL, the downloaded file is broken. I manually located a direct CDN media URL (on Instagram) and fed it to the tool. The resulting file:

• Has no audio -- these platforms serve video and audio as two separate adaptive-bitrate streams (standard DASH-style delivery). The tool grabs only the video stream, with no attempt to detect or fetch the paired audio stream.
• Won't play in QuickTime -- the video track is VP9-encoded inside an .mp4 container, and QuickTime doesn't support VP9 at all. Even a correctly-muxed file would still fail there without a warning or fallback.

Suggested fix: When a supported "adaptive streaming" site is detected (Instagram, Facebook, TikTok, YouTube, etc.), the tool should identify both the audio and video CDN streams, download both, mux them into one file, and transcode video to H.264/AAC if the source is VP9 -- so the output "just works" in QuickTime, Photos, iMovie, etc. without requiring the user to manually run ffmpeg.

I had to manually extract CDN URLs from network traffic and use ffmpeg to fix this myself, which shouldn't be necessary for a tool marketed as a one-click downloader.

Thanks,
Mike