I tried running something like this on my own, but I got OOM errors pretty quickly. 4 gigs isn't a lot when it comes to video processing. Hopefully wasm64 and WebGPU will make it a lot better.
I think this is as a result of the video have to be uploaded into RAM to be processed, this is definitely something I want to try to fix where I access the videos on the native file system to allow much larger files