Quick note on tools
Mostly for my own sake, though I suppose it'll also be helpful for others trying to download videos - there's a host of sites for downloading Twitter videos, but the only one I found that actually worked for this one was savefrom.net, so if others are failing and claiming there is no video in a tweet, try this one.
Also, in order to download HLS videos in general, say the one in this article, you can do the following, once you have the M3U8 file's URL (which you can get from a network inspection tool, e.g. the Network tab in Opera's "Inspect Element"):
ffmpeg -i 'http://example.com/video_url.m3u8' -c copy -bsf:a aac_adtstoasc output.mp4