Alright Fuzz.
I'll teach you (I taught myself. Very proud of me. Hehehehehe.)
Anyway. The first thing is to d/l the YT vid. Use Keepvid.com - I love their quality.
Anyway, if you have Sony Vegas.. it doesn't matter what type of vid you download. However, if you're going to use Windows Movie Maker, d/l the highest quality MP4 available on the site. (& then you'll have to convert it into .avi. I suggest using Pazera Free MP4 to AVI ~ Google it.) In any case, always d/l the highest quality available - even if it means more MB used.
Alright, so you've d/led the vid, and converted it. Now comes the fun bit. Open Windows Movie Maker... and play the vid. Pause where you like, and there's a button on the mini screen on the right hand side - it's a pik of a camera... and for every frame you pause on, press that button and it saves the cap.
Evenutally you'll have a fair few... and then you know how to upload. (quick&easy? Use PhotoBucket. Seriously.)
& there you have it. Making your own caps. LMAO.
Any questions?
<3