In truth I'd be more concerned about your available dexterity in operating the video of the 5G nano if you said you had limited movement in your left hand. You can easily run the video app with your left hand alone once the app is launched. In fact, I think it's actually better to use one's left hand alone, because it makes it easier to hold without getting a finger (of either hand) in the way of and blocking the lens.

With your left hand, you can hold the nano as if your holding a pen...or a paper airplane...pinching the unit while placing your left thumb over the center button on the click wheel to turn the recording control on (and off). As long as the forefinger is kept relatively low (it's easy to do) there should be no problem with it interfering with the lens. Video quality isn't all that great, but it's serviceable. Just don't expect something that will look marvelous on a considerably bigger screen, because the results won't. But for casual remembrances, it's actually an adequate device.

For music the SQ of the nano is okay, but it's nothing to write home about. And with vid display it's pretty average; there's only so much a small screen like that can do.