You just have a bad computer. Mine converts it real quickly (almost equal to the length of the animation). Also recording with Camtasia gives low quality vid, unless you are ok with that.

Do what Resh said in the previous page.
Change the dimensions to low one and the video codec to the 9th one.

Quote from Ashish9

Do what Resh said in the previous page.
Change the dimensions to low one and the video codec to the 9th one.

I did and it didn't work. Man my computer is bad :( Well I got 2 options: upload my videos soundless, and in my description have a fileize link that has sound. Or try ErrorBlender's option.

Ok, in flash, select file>export>export movie
Then from the drop down menu of File Type, select mp3 or wav. Export in your desired quality.
Open up windows movie maker, put your soundless movie in the timeline and the new music over it. Export.