It's actually surprisingly hard to intentionally damage most magnetic media (except audio tape and really cheap magstripe cards and you probably aren't going to see either today) with permanent magnet, so one can safely assume, that this is not a problem.

from TFA:

> Luckily, the magnet is not strong enough to wipe out credit cards nor will it negatively affect electronics or computer monitors.

> Luckily, the magnet is not strong enough to wipe out credit cards nor will it negatively affect electronics or computer monitors.

He doesn't specifically say anything about tapes or Hard Drives, but I doubt it.

I've tried, and from my experiments it has not been strong enough to destroy anything.