ESR is a homebrew app made specifically to work with FMCB to allow you to play backup DVD discs without the need to swap. You will have to patch the ISO before buring to disc. CD backups are not supported.
Short tutorial for games:
1. Put your original game in drive and make image of it.
2. Patch it.
3. Burn it.
4. Put it in your PS2 and launch ESR (direct DVD version).
5. That's it!
Short tutorial for homebrew apps (launching from DVD):
1. Start new compilation of DVDVideo.
2. Put all necessary DVDV structure files.
3. Put your SYSTEM.CNF in root directory of disc (remember about the ;1 ISO version extension).
4. Put apropriate executable (same as in SYSTEM.CNF)
5. Make sure the DVD will be hybrid UDF/ISO.
6. Burn it.
7. Put it in your PS2 and launch ESR (direct DVD version).
8. That's it!
... or just put your homebrew app as mcx:/BOOT/BOOT.ELF or mcx:/B?DATA-SYSTEM/BOOT.ELF, whete mcx is either mc0 or mc1 and ? means reagional code. Now run the second file (mcard version). Though, the best choice is to have uLE in one of the paths and launch other apps from it.
ESR Official Forums - You can find compatibility info for games , patching apps and lots of info to get you going.