Okay, what you mean with your 700MB medium is a CD, a DVD looks the same but can hold more data.
What your friend did was burning a VCD (Video CD) or SVCD (Super VCD), which compresses the original video to fit onto a CD. But you loose a tremendous amount of picture quality, as it uses an older codec called MPEG-1, which is originating in the late 80s and has seen some development in the early 90s.
Your TV episodes use the Divx codec, which is based on MPEG-4, a far more efficient and superior codec to MPEG-1. And it's not that old.
You can use Burn to make VCDs and even SVCDs.
But a VCD will only hold 80 minutes of video at maximum, an SVCD 60 minutes, as it offers a slightly higher resolution than VCD.
You also need a DVD player capable of CVD or SVCD playback, so be sure to check that. If your player can do that, check if it plays .avi files encoded with the Divx or Xvid codec, as that would be the better solution, as you can burn two episodes onto one CD without conversion as normal data thus there would be no quality loss.