No each quote wouldn't refer to a file name. Because the sound files are all contained in one big file(well several large files, but there are many sounds grouped together each encoded in either PCM/flac). You can easily look for the beginning of the flac portion and split all of the audio into seperate files by using the offsets. There was a script online that actually did it all for you. So my guess is one would look at IDA for references to the offset of that sound package in memory. IE: The game loads the zmb_common.all.sabs file into memory and then one could find code that referenced those memory locations at each offset in the sabs file contained in memory. Then one would know which code portion triggers Richtofen/etc. to say which quote by following the xrefs back to the originating code. I'm not that experienced with IDA, but i'm assuming it would go something like that.
SABL files appear to be encoded with PCM
SABS files appear to be encoded with FLAC
For all of the zmb(zombies) sound files you are looking at around ~800MB of audio. One could take all of those files and re-compress them to aac or something to get it quite a bit smaller for people to have access to them. But i'm assuming that's how all of these quotes videos were compiled by splitting them and then going through these files and grouping them by an individual. They are definitely grouped by person but there are "A LOT" of quotes for certain individuals, so it would definitely take some time to sort through them and group them together.
Here is the script I mentioned above.
http://www.mpgh.net/forum/616-call-duty ... tview.html