I download TS files sometimes, mostly in order to extract the subtitles from it.

Then I watch the TSes w/ subs and there are some interesting ads in there. My idea is to split out the ads and upload to YouTube. The How To is not straightfoward; I was hoping someone could help.

I suppose one of the more straightforward methods might be to use avidemux.
http://fixounet.free.fr/avidemux/

A more accurate and dependable method would be to use AviSynth, but it has a bit of a learning curve. http://avisynth.org/mediawiki/Main_Page