Ok, I dropped Virtual Dub due to it's completely incompetent codec handling and gave Avidemux another try. So far, I was able to render a comletely part with some color correction (for some reason, Virtual Dub displays it exactly how it looked while playing). Too bad that I can't just have a nice splitting feature in Avidemux and do instead have split it manually. I mean this isn't too bad and gives me some opportunities to have smoother endings. However, I think it's the best to stop parts after 14 minutes to avoid this completely. Rendering takes so much time - best thing to reduce the editing steps to a minimum.
So yeah, there's progress (though not as steady as I'd like). However, I didn't record anything in English because I'm not yet "skilled" enough in spontaneously talking English while playing. I tested it while playing Stalker and it didn't end really well I think. It might be Stalker itself. I mean the game's not really filled with stuff and I know it in and out, so it's no wonder why I'm having a hard explaining everything I do by default. I guess I'll do Let's Plays in both languages in the end, depending on whether my English is apprioriate enough or not. There are also some games I can't and want to play in English because I only have the German version or because they're too "random" in terms of language. For example, it took me ages to find out what "pewter" was until I fired my favorite web dictionary. I wouldn't want to let this happen in a live commented Let's Play.