No, selecting GL for video output is done in your media player. I don't know which one you're using, so I can't tell you how

If you're using SMPlayer, which what I'm using myself, then you do that in "Options->Preferences->General->Video tab->Output driver". There you select "gl2 (yuv)" in the drop-down list and restart SMPlayer.
Enabling VSync for GL is done in CCC (Catalyst Control Center). It's a GUI tool that comes with the Catalyst driver, so it should be somewhere in your applications start menu.
GL could be a bit faster, but nothing really noticeable.