Look in /usr/src/linux/Documentation/devices.txt. This file lists all devices
that linux supports and tells you whather it's a block device or a character
device and the major number. For instance, block-major-8 would be the module
for the scsi drives. If you don't have any scsi device, then I guess you can
just ignore the message, some distributions have scripts that try to load more
modules than they actually need. If you do have a scsi drive, then that drive
won't work if Linux can't find the driver for it. There may be two reasons:
either the module does not exist, in which case you need to recompile the
kernel and include the driver you're missing, (usually you compile it as a
module), or the module exists, but linux can't find it, in which case you need
to create an alias in /etc/conf.modules.
Example: I have a sound blaster sound card, and the driver for it is
/lib/modules/2.2.9/misc/sb.o. Then in my /etc/conf.modules I have a line
alias sound sb
I don't have any scsi devices, nor the other devices whose modules you're
missing, so I can't tell you what they should be aliased to, but I'm sure some
kind soul will.
As for video4linux, if you have problems (or question) you may want to join
the video4linux mailing list, if you haven't already done so.