Flv to dvd burning tips?

yo everyone,
okay, so i have these tons of flv files and i want to watch them on my dvd player. so, to edit my flv files ya know, merge, cut, etc i couldnt do it directly so i converted the flv files to avi using flv to avi converter. and then i deleted the parts i didnt need using windows movie maker. and finally burned the files to a blank dvd. but the audio is messed up. its scratchy. the video is okay though.
so, is there an easier way to edit flv files and finally burn them to a dvd?
i have nero 8 but converting flv to avi takes a lot of time. (2 hours 50 seconds to convert a 26 minutes file from flv to avi)
thanks in advance.