There's isn't an way for YouTube on PSP unless you have Custom Firmware, witch is pretty unstable and risky to install but hey the reward for not coward and install it is huge!
I have it. But back on topic, no there's isn't any other way.
i was talking about steve put risky to install when its so damn easy
I said that it's risky in the way that you have to hack your PSP and things may not work and you can brick your PSP.
Its only risky if u dont do enough research. Im runnin 5.00 m33-6 CFW (I know its kinda old, but these new CFWs aren't 2 reliable) but you dont have to flash your psp to run homebrew, try downloadin ChickenHen Mod if your firmware is at 5.03. Check out psp-hacks.com Dats where I figured out how to hack my 2000