You should have the video switcher on your PC in the Slayer's ISO. You can extract the ISO and get the video switcher program. You can burn to a CD-RW, which is the easiest to read in the Xbox from everything I have read. You can also get the video switcher program from Xbins. There are a couple out there and you will need to read the instructions since you can't see the screen.
You may need to make a dummy file to put on the CD also. It makes the CD larger and lets the Xbox read it more often. Here are the instructions for making a dummy file.
Pulled from a tutorial written by circusmonki.
Make a "dummy" file of about 4 GB and create another ISO but this time include the dummy file in the ISO. It doesnt matter what you name the dummy file. To make a dummy file copy and paste or type (whatever suits) this into command prompt in windows XP:
fsutil file createnew d:\temp\4gbDummyFile.txt 4194304000
If you are using a CD, you would leave the last zero off to make it a 400meg dummy file. The above is for a DVD.
What did you do to get into this predicament? Are you sure the video was changed?