Add a "subscription channel" start postphoned - get the video information but don't start download. Else https://www.youtube.com/user/NASAgovVideo will make 4k downloader crash and crash and crash...

When adding a subscription to a channel we need an option to "only list", "get information", "start download right away".
https://www.youtube.com/user/NASAgovVideo ist a nice example which will make 4kdownloader crash repeatedly. Only if you are lucky it starts and asks "postpone?", so you have more control over it's crashing.