Currently I'm having problems with it (problem playing videos: stopped halfway, etc), which I think is caused by overheating problem.

Yes, it gets really hot 🙂 I almost burned my finger recently. And there's this guy posting photos of its mk802 with its melted casing. Crazy.

I'll buy a heatsink for it tomorrow.

In case it's not a hardware / overheating problem, then I'll need to start considering other solutions, for example: upgrading the firmware, replacing the android with Linux, etc :

XBMC for Android : https://www.miniand.com/forums/forums/1/topics/136

Uberoid (latest firmware + extra fixes) :
http://www.techknow.t0xic.nl/forum/index.php?topic=3333.msg38123

Howto replace mk802's firmware (incl. link to the LIveSuit) :
http://www.timingpower.com/support
http://www.envythisstuff.com/techtalk/mk802faq.html#updatefirmware

Linuxes @ mk802 :
http://www.androidtablets.net/forum/w2comp-com/46166-ubuntu-12-04-rikomagic-mk802-mk802-ii.html

CyanogenMod 10 @ mk802 : 
https://www.miniand.com/forums/forums/development/topics/cyanogenmod-10-full-working-with-internal-storage

Other stuff : must-have apps fo mk802 :
http://www.rikomagic.co.uk/forum/viewtopic.php?f=2&t=946

I'll post the solution which works for it.

http://quattromagic.com/faq