Cellulo is donationware. This means that you don't have to pay anything in order to use it, though you are encouraged to make a donation to its author. To know more, please read this page. Thank you.
You might also be interested in downloading the following QuickTime codecs:
- DivX (official)
- DivX (FFusion)
- 3ivx (overrides the official DivX codec)
- XVid (official DivX codec needed)
- AC3 (audio)