If anyone out there has a solution to this, it'd be GREATLY appreciated; I'll even spam this fix on all these other forums that I've joined just in an attempt to find an answer to my problem. "Thanks" in advance!
Well you have an Atom based Netbook and most likley the issue is perfomance capabilities an not video memory. That said, the only way to increase video memory is with a system BIOS setting which it appears Dell did not make available for your Netbook.
I'm not entirely sure about this, as the GMA 500 is a variant of a PowerVR core licensed by Intel, but: the GMA9x0 series allocates it's memory dynamically on a "as needed" base.
As far as I know the GMA 500 sports no advanced video acceleration technology and the Atom CPU is nice in regards of power consumption but also rather slow considering typical desktop or laptop (not netbook) CPUs. Youtube, esp. if watching HD content, might push your netbook to the limits. My Asus eeePC 901go for instance is definitely a tad to weak to watch youtube HD videos without stuttering.