it depends on your connection speed and also the file size you're uploading... the smaller the file the faster you can upload and complete processing...
It is recommended that you upload wmv file format... good quality and smaller size.. so faster upload... and also faster processing.
Using windows movie maker -- you have to save it into the proper file format, that is wmv file (use the "save movie file" on the menu at the top left) before upload..
--for best editing....
use windows movie maker (included in your windows machine)... it can help you make beautiful slideshow or video clip(e.g. mixing your songs with pictures/video/etc).... then save it as video file such as wmv file format... finally upload.
or .. Just get those clips you want , save & convert them, and then mix/match with pix/sound/etc using windows movie maker to create new masterpieces....
this will help you.... Use 'zillatube'. This is the easiest (and also the fastest) way.
Zillatube produces mpg/mp3 formats from youtube that are compatible with windows movie maker(or media player), and more.
It is very easy to download and convert videos. Then edit those converted mp3/mpg videos with windows movie maker... save your file as wmv and then upload.
It works very well....just google search for "zillatube", and select the first search result for download...