certain videos wont load on ff but work fine on google/IE

hi, hope someone can help, ive had a virus and ran several different programs to remove (ads by name) however now ive finally fixed that, firefox wont play videos on vodlocker, gorilla vid, mov pod etc. ive gone on to google chrome and all links work fine but lets face it no one wants to use google. i have installed, flash player, windows media player, quick time, shockwave flash and silver light but still nothing. ive already started it in safe mode and tried and that didnt help. everything worked fine and ive never had any problems before on the sites, any advice would be great thanks!!