RSS feeds: How to reformat/rewrite/restyle? Using views? e.g. convert youtube text list of videos into thumbnails?
Yes Views will be the perfect module choice for you, there are many ways to tweak the output with Views &amp; it has built in Feeds support.  Google about drupal views rss feeds, you'll find a ton of info.  When you install views there is an example rss feed view you can enable and take a look at to see how its done.  As for the thumbnails if your using emfield you should have the option to display thumbnail when tweaking the field output from within the View.

Good luck!