If the Movies archive of CD2 isn't working, you probably found your culprit. The "Disk 255" error is caused by the game not being able to access the movie which is to be played when you enter the Friendly Arms area for the first time.
For the .ini entry, you would indeed add that line to your baldur.ini of BG2.
I installed everything following the readme instructions. When I enter the Friendly arm in, the game says Load Disc 255" error and shuts down.I found it really dissapointing because i enjoyed tutu and was planning to play again through the whole saga with bgtutu. I read some other topics about this and some say to copy manually the movie files to the bg movies dir. But i tried that and it didn't worked, when i copie the movie from cd 2 there is an error, rendunantiefault.Probably because there is an tiny scratch on the cd. I also tried to set Disable Movies=1 in the baldur.ini in the bg 1 directory. Are there other solutions or did i something wrong, (like not picking the baldur.ini in the soa directory). Thx for any help