(A) First of all, you have to to author the .avi to create a VIDEO_TS compatible folder; you can, for instance, use fffmepgX (here)

(B) Then, through
* the DVDimg tool of ffmpegx
or
* DVDImager (here)
you'll convert the VIDEO_TS folder into a 'ready-to-burn' disk image file.

(C) Then user Finder/DiskUtility to burn

Note: Toast7 or Popcorn (commercial, here performs (B)+(C) directly

Phil