Fix play issues with large video files

[taoeffect]

Problem

If you set the max file upload size limit to 300MB and upload a ~287MB video, then try to play it, it will download the video but not play. On Firefox, it gets stuck here:

This was discovered while testing this PR per @corrideat's request: #3042 (review)

Note that this happened both in that branch and on master (verified by reverting commit a4ef77b90be3ee6a58343b391701ba05351cc7f9 from that PR).

Solution

Not sure.

In general we're planning on chopping up large videos into smaller chunks (as this will greatly speed up playback of long videos), so this might get fixed as part of that.