Currently there's a 2-GiB soft limit (overrideable by sysops) and a 3-GiB hard limit for estimated size of transcode output, as a precaution against runway super-high-res/long conversion jobs.

The hard limit should be safe to extend to 4 GiB, or possibly higher (blocked on T191804 and T191802 ), as long as Swift can handle the files. half-hour 2160p videos end up hitting this limit at the highest resolution. :)

Raising the hard limit will allow long videos to be run as long as someone overrides the default soft limit at 2 GiB.

I'll put this in my queue for next week, so self-assigning.