i'm new to shooting video and importing, editing and burning to disc. i have a simple question i'd like an answer to. discs are much cheaper than mini dv tapes. so i'd like to burn all to disc and then reuse the tape. my hope is to avoid paying $5. a pop every time i get to the end of the tape. if i record over on my mini dv tapes, how many times can i expect to do it without degrading the quality of the output? also, how will i know when to get ride of a tape and use a different one? thanks.