Videos fail to upload to Youtube

Honestly, I don't even know where to start. Between endless spinning wheels and this most recent problem, I'm quickly being turned off by Apple. In some cases, this has a good deal to do with my ignorance, but I don't see how these products could be described as "intuitive" since a problem like should easily be fixed with a simple search.

I hardly ever upload videos to Youtube. I had no problem a few years ago after returning from a vacation. The other day, I tried again. No such luck. In the last two weeks, I have tried to upload several very short videos, none of them longer than 10 seconds, all have failed. For the heck of it, I attempted to upload one of my old vacation videos and was successful.

All these videos were taken with the same camera - download from that camera to iPhoto - then uploaded to Youtube. What could be the reason that videos that are several years old have no problem with uploading and videos taken in the last week won't upload.

I have searched the actual message given by Youtube (It will be included at the end of this message) and I get almost nothing. Youtube Help Center, for me, seems pretty much useless...it's as if they're speaking a language I don't understand.

Where are my Quicktime settings anyway? Do I need to be Quicktime Pro? Why can't I just select the file from iPhoto, like I've done in the past, and upload it? Do I somehow have to export this movie from iPhoto to iMovie? I just don't know...obviously.

I'm using Mountain Lion (10.8.2). Quicktime is version 10.2 (603.3).

Please let me know if anymore information specific to my machine is needed.

ERROR MESSAGE FROM YOUTUBE:

For better results, adjust your Quicktime settings to prepare the videos for internet streaming. For more information, visit our Help Center.