[FEATURE] [Youtube] Add filter for stream announce

[slimpdev]

Hello.

Now, if youtube streamer make Stream announce (with countdown) - chatdownloader see it as Live and start session.
The option to ignore announcements is very lacking, I have an inactivity timeout set up and because of this it creates a lot of small files with chat logs. Maybe there are already some options for this? For example, a minimum number of online viewers?

Thanks.