As Player i use QQPlayer which is able to play all file formats. (flv, avi, mp4....)
And the location for the pictures? Come on.
Copy your pictures from time to time on your external SD and the problem is gone...
As browser you have to use Dolphin Mini which supports Flash and all other things like gestures, bookmark sync, fullscreen and a very good speed...
MiUi is great, smooth and beautifull.
Phone: Samsung Galaxy S GT-i9000
Firmware Version: XXJVS (2.3.4)
Mod: Simple Honey
Kernel: hardcore@SpeedMod -k16-6#10