Video encoding isn't the biggest user of memory. Working on a full-page, four-color, glossy ad for a magazine in Photoshop will happily use lots more and still be hungry. Servers will use up all you can throw at them, too. Webservers will generally cache the most recent requests in memory, so you can get a definite speed advantage there and mail-filtering programs like Spamassassin tend to be huge resource hogs and, depending on how much mail volume you're handling, will definitely benefit from several gigs of memory.