Thanks for the video.
Sounds a bit plasticly and not muffled. I'd check your fan to make sure it's free (no ice inside). Could be a bearing going. Put your hand right on the top middle of the unit and see if you can feel the clicks there.
Unfortunatly the other noise maker could be your compressor. (big bucks unless theres a warranty still floating around but it looks older so doubt it).
As always, pull your outside disconnect before messing with the unit, it is energized with the heat off and there is often a heater inside that runs. You can unplug the power to the fan (mark wires first) to see if the noise goes away. Do not do this more then enough to listen for the noise and dont forget to hook it back up when done.
If it's the compressor, it may be time to evaluate your whole system for a possible upgrade.