it is possible with certain hacks such as linux or podzilla video players, but not recommended. you can really mess up you ipod and be in real trouble. also, think about how much video can you hold with 2 or 4 gb?
Never heard of one single ipod being messed up from running ipod linux or rockbox. Basically you can always flash it back. Don't think ipod linux is officially supported yet for the nano though and rockbox I don't think has video.
It seems though if you read some of the fouroms ipod linux or podzilla really screws up your ipod. The unlikely cases are when the instructions are followed to a tee. You should be carefully with a sensitive thing like you nano.
