Some of the most popular video formats supported by YouTube (directly from their Help site:
• WebM files--Vp8 video codec and Vorbis Audio codecsThe only error message on the YouTube upload page was something to the effect that "There is a problem with your file." After much trial and error, here are some things I learned about video file formats and YouTube.
• .MPEG4, 3GPP and MOV files--Typically supporting h264, mpeg4 video codecs, and AAC audio codec
• .AVI--Many cameras output this format--typically the video codec is MJPEG and audio is PCM
• .MPEGPS--Typically supporting MPEG2 video codec and MP2 audio
• .FLV--Adobe-FLV1 video codec, MP3 audio
Believing the .MOV file format might be the problem, I tried about half a dozen free video converter software apps on my long video. None of them would convert a video of any length for free, despite plastering the word "free" all over their download sites. 100 MB is about the limit without paying extra, including online converters. I finally came across QTAmateur.app at the Mac Update site. Despite the dopey name, this little software is very powerful and converts to many different video formats quite easily, including those usable by PCs and mobile devices. And it is an absolutely free download. Use ("Export" to make the conversion.)
This was a fortunate find, as I want my videos to eventually be playable on mobile devices as well as on desktops.
I found the information about how to get the extra size files (the link didn't just jump out at me) by searching videos in YouTube (of course). I found several, the best and simplest of which, I think, is How to Increase Your Upload Limit on YouTube.
.avi format (a little clearer, below) or .mpeg4 at my YouTube channel. Just FYI, this was originally a Powerpoint slideshow saved as a Powerpoint movie. I may yet get around to putting the .mov version up, but you can play it with most video players on most platforms anyway.