"dvd drive with 4gigs of ram" ... "Spin 4 times" ...wut?
I think you have the wrong idea about caching. The main purpose of a cache is to buffer the data flow so that the data output remains constant even if the input is variable. And most optical drives only have a cache capacity of 2-8 megabytes
, which is usually all that's necessary for that purpose. But no matter what the cache size is, it still has to get the data off the disk in the first place, and that depends on the drive's read speed.
Unless your drive has a read speed that's so fast and a cache so large that it can buffer an entire dvd (usually several GiB) in the few seconds before you start playback, you're going to have spinning going on while you're watching.
Of course, you could just rip the entire disk to your hard drive and watch it from there instead.