- add movies to channel above free slot (no check for 2 free slots)
- add sound to the free slot
This code is bad just by looking at it :[
I guess that worst is, that it silently overrides channel operator property.
We can not set channel in python anyway and there is another code that can override decision made by this operator...
This seems to be rabbithole I don't really want to deal with at this point - see T59540: VSE timeline manipulation API