Tacori, do you have iMovie? You should be able to render to other formats that are much smaller. I don''t have a mac, but I have software that I use and usually render to a wmv file fit for the Internet.
Buy Quicktime Pro for $30 (I swear it is worth it- I use it ALL the time) and you can convert AVI to AVI but medium quality to make it smaller, or better yet convert it to mp4 will make it much MUCH smaller and you can post it online!