Also note, the medium sized PB2 padded bags which Australia Post sell are too narrow to fit both DVDs or Blu-Ray discs. Recently they shrunk the PB2 bags from 151x229mm to 146x223mm, but both sizes of PB2 bags are too narrow.

If you need to send two DVDs or games to someone, it is cheaper to use a larger padded bag but make sure to put the cases side by side. It should cost either 3 or 5 stamps ($3 or $5 as of 2017) depending on weight (Australia Post does not have a 4-stamp letter category for some odd reason, although logically it would have been in the 251-375g bracket). If you put a DVD case on top of another it will be considered a parcel. Just remember (again) that 500g Parcel Post is cheaper than 500g Registered Post, so if you need tracking for heavier large letters send them as a parcel.

The following items will not fit in the letter gauge after putting in a padded bag:
PlayStation 1 games (in the regular fat cases or double CD cases; standard sized CD cases are fine)
Sega Saturn and Dreamcast Games
Super Nintendo (SNES) and Nintendo 64 cartridges
Nintendo DS clear cases (usually European-made games have these e.g. Ubisoft; the normal black cases are the same thickness as a DVD case)
Game cartridges e.g. Nintendo, Sega, Atari
Anything else which uses a case thicker than a standard DVD case

Note that Sega Master System and Mega Drive games were designed to be the exact dimensions of an audio cassette case. It may be possible to barely squeeze a game through the gauge for 2 stamps but I don't recommend trying. I have never sold tapes on eBay so I don't know if they fit. A tape without a case should be fine though.

Of course, any game which has its original cardboard box (or plastic VHS style boxes in the case of Sega) will automatically be Parcel Post.