I now have pretty much all of Giant Bomb's Twitch videos from 2010 to 2014, and in 720p from early 2011 onwards (there are still some videos that have URLs that you simply can't download or view any more). This equates to:
1,422 videos.
754 GB.
Do you have a record of the failed downloads at all? Each API request returns multiple versions in different resolutions, so where the original fails, we could probably try a lower quality one.