temporary fix for the time jumps

I have added -t 72000 (20 hours) to force ffmpeg to mux the file when a "time jump" happens.

For some reason every job I've seen so far (at least 6 in total) was to 20 hours or more.

I think It's a safe value, which won't cause any troubles. There is no chance recording a live stream for 20 hours without interruptions anyway (my record is 3 hours).

https://github.com/rg3/youtube-dl/issues/2213