Recompressing an 1.5-hour-long 1080p H.264 video on the iPad? I barely think it's feasible - it'd take just too much time, at least an order of magnitude more than doing the same with a desktop Handbrake. If the recompression doesn't crash before finishing, that is.
Next time you shoot and know you may want to share it use a client with settable bitrate, setting the latter to, say, 2.5 Mbps, which, if you shoot from a tripod or the like, is generally sufficient to record lectures. Or, use a jailbreak tweak to do the same in the camera client.
If you aren't afraid of doing some betatesting for me (I don't have an rMini), I can even release an rMini-specific version of
my well-known camera enhancer tool, which is also capable of directly setting the bitrate.