Well... I have made 26 videos worth of Gabriel Knight 3 outtakes.
Notes: All the audio file code's names will roughly show you where and when it was used. They all have a matching YAK file, which contains the subtitle information, and lip sync.
In cut lines from discussions I like to blend them in.
I made these while I was digging - there were times when I wrapped it up, then later found that there was still more fun stuff and made another video. There were some files about objects in the scene outside the hotel, that I later found was part of the Original Cat Hair Moustache (OCHM).
And of course there are lines that I later found were in.
https://www.youtube.com/watch?v=LKow7OaF1_41a: This one begins with odd moans.
The infamous day3 2AM closing video (it's called Destiny Catches Up in the Time Block Bible) is silent, but originally it had text.
https://www.youtube.com/watch?v=VXHRaLrFIUEHors Series: Lines that Madeline says on the phone, the first two didn't make it into the game. Probably because the five minute time gap is tight enough as it is.
https://www.youtube.com/watch?v=6WE4sz1aJcQ#1b: Wilkes singing, and The Cat Returns. (which is also an anime in which Tim Curry has a voice.)
https://www.youtube.com/watch?v=j8wCa4D59aI#1c: One removed location, the Tour Magdala Staircase, has quite some fun lines!
https://www.youtube.com/watch?v=3hfP6Lmh4UE#1d: Deleted line from the museum harp tapestry that was too risque.
https://www.youtube.com/watch?v=8tCHo-e5Bn8#2: Burgling lines
https://www.youtube.com/watch?v=i4nsu_dLh6I#3: Tree lines that I later found were from OCHM.
https://www.youtube.com/watch?v=sCahpwg6O1s#4: Game teaser audio
https://www.youtube.com/watch?v=INuiWvpZSHI#5: Deleted scene between Gabe and Wilkes.
https://www.youtube.com/watch?v=-aUaT1frfgs#6 turned out to be in the game.
https://www.youtube.com/watch?v=p2PyvtB1Bhg#7A: A string of Gabe lines. I included the Clue reference deliberately so that the people at the Tim Curry fanforum I frequent could hear it too.
https://www.youtube.com/watch?v=hTXssAJcLeU#7B: A string of Grace lines.
https://www.youtube.com/watch?v=vW-XRa1WRcw#8: Missing lines from the temple chessboard room, hinting towards an extra puzzle.
https://www.youtube.com/watch?v=CQgA3B7xDFg#9: Deleted from the Montreaux interview
https://www.youtube.com/watch?v=Dxamibd8U5Y#10: Missing temple room. One large puzzle was cut from the temple. I got to ask Adam Bormann, he didn't remember it and promised to check if he still had some art related to it - the GK4Campaign forums unfortunately closed down before he came back with an answer.
It seems like a maze with puzzles relating to the quaternity (square). This would go between the Pendulum/Scales (circle) and the Solomon (hexagram) puzzles, so the map geometry is repeated in the temple. Nice huh! The artwork is from a tile that isn't used in the game, but the figure can be seen in the credits.
https://www.youtube.com/watch?v=p8TvWLpYgIQ#11: Deleted lines from Emilio confrontation
https://www.youtube.com/watch?v=H-S5BQdapmk#12: At Wilkes at l'Homme Mort.
https://www.youtube.com/watch?v=W8xWaZq_n5I#13: Miscellaneous Gabriel lines
https://www.youtube.com/watch?v=vBOk2t3Nt9w#14: A lot of miscellaneous Grace lines.
https://www.youtube.com/watch?v=itZ_PZaDC0s#15: Remotely interesting unused lines that I clustered together.
https://www.youtube.com/watch?v=cyLSx5ueaKk#16: Chitchat with Simone that didn't make it.
https://www.youtube.com/watch?v=KMhvsezo_Q0#17: Removed dialogue with Larry.
https://www.youtube.com/watch?v=dA25IgQdLMY#18: The REAL Cat Hair Moustache!!! Includes original artwork from the puzzle. And there's a line from Grace about a Wet T-shirt Night.
https://www.youtube.com/watch?v=dgj-1gkjszM#19: None of these have a matching YAK, but you can guess where they'd go...
https://www.youtube.com/watch?v=cVqngRClt9s#20: Outtakes by Mallory (black-haired Scot, voiced by Tom Kane) - some are from lines that would later go to McDougal.
https://www.youtube.com/watch?v=7AgrrsUvTJM#21: The bridge game was supposed to give you another opportunity to get Emilio's fingerprint.
https://www.youtube.com/watch?v=Re8gDeC1k4g#22: Originally there'd be an alarm clock in Room 25.
https://www.youtube.com/watch?v=JKssvcOwEw4#23: Two missing lines from the Temple discussion just after you crossed the flickering tile bridge.
https://www.youtube.com/watch?v=tCSp3hEzXyI#24: Missing lines from the pendulum room: you were supposed to be able to look at the objects on the spinning disks. Instead Gabe just jumps there.
https://www.youtube.com/watch?v=aGPflzsK37k#25: At The Site, you can click on the surrounding landscape, it's an object - but it's missing its lines. Here they are!
https://www.youtube.com/watch?v=yNHp_EnRMf8#26: Missing Location 3
This is an entire location that was cut - there was nothing here besides roadsigns.
Back when I first started digging in 2010, I briefed my findings straight through to the GabrielKnight4Campaign forum. It's now gone, but there's Archive.org. At one point, Adam Bormann showed up and answered some questions. The site is now gone, but there's still archive.org!
https://web.archive.org/web/20101228134446/http://www.gabrielknight4campaign.com/forum/viewtopic.php?f=2&t=294&st=0&sk=t&sd=a