Hi, the Youtube video has a private status so we don't see it...

Anyway, if the magnets are loose and you want to try fixing the motor, find some heat resistant epoxy and glue them back. Be very careful not to change the polarity of the magnets while working on them! They should have some sort of markings but if not, use a marker pen or such to mark them before removal.

If you need any further help, people on this forum can probably give you better and more detailed instructions: http://www.rcgroups.com/power-systems-13/