Nice updates.
More suggestions
1. I think you should put a new setting where the screenshots will be saved. Like create one more like to select the screenshots folder because what people do is, they'll upload the screenshots in the thread, having them inside the rar isn't so useful.
2. The renaming feature shouldn't rename the actual video files. I think it'll be cool only if it only renames the RAR or you should put a checkbox where it might say "also rename files?" Cuz some don't touch the original files inside.
3. MKV works too. I tried changing the extension to .avi from .mkv and it worked and even MTN thumbnailed the video.
4. Should the renaming and all the questions be asked before moving to Temp directory? because I tried doing a 1.09GB file and it took quite look, so we'll have to stay in front of the computer until it's moved to Temp dir and asked for the new name. It'll be better if it can ask everything before the start

So the user can get some free time.
5. Your raring sizes are off.
100MB is not 100000KB
it's suppose to be
100MB = 102400KB
200MB = 307200KB
400MB = 409600KB
I tried putting 400000KB, hoping to get 400MB parts but I got 381MB parts xD
Thanks for coding this. It's going to be a big help!