Apologies - let me try and be more clear. The user loads a local movie into the browser, and the browser then processes locally with ffmpeg. The movie started on the client and stays there. If it is less than 2GB then no problems. If it is larger then it hits this limitation. (I am taking the results from ffmpeg and sending those server side, but those results are always << 2GB and therefore no issues).

Maybe the suggestion is to only load < 2GB into ffmpeg in the browser? I could see how that would work for the 1st chunk. But the 2nd one and beyond would not be valid.