Stars Guide is like a Musical documentary showing what goes on to create a musical (features interviews, photo shoot, musical recording, etc.)

Eien Omake has footage from the Stars K senshuuraku, a documentary on the creation of Eien Densetsu musical, and finally fan kansha footage.  Since it has Stars K spoiler footage, you should see that musical before seeing this tape.

FFS LD Omake, the top 10 favorite songs from the first stage.  Basically just a clip show hosted by Mochizuki and Ryuji.  I don't remember if these are spoiler clips or not (I think at least one of them are), so you should see the Stars-FFS musicals first if you don't want to be spoiled.

Bad:
Kind of short

Good:
The ultra rare tapes from First Stage.  The only thing more rare is the First Stage Hozonban and Senshuuraku tapes.

Bonus:
Since these are bonus tapes, you can't buy them officially.  So they're pretty rare stuff.  It's a mix of documentary and fan kansha clips, so it should be kind of interesting.