UPDATE: Just tried this recently after a bit of a break. It seems Animoto have changed something about their .mp4 downloads because polybore’s original way of editing animoto videos no longer works (although it still works with animoto .mp4 files from when polybore first wrote this). Not to worry have found a new way of doing it. You need this http://www.pazera-software.com/products/mp4-to-avi-converter/
Be careful when downloading it. don't hit the largest download button, it is an add for something else. The download button you want is smaller and blue. Be patient the download ite tries to sell you stuff, ignore all that and you will get pazera in the end. Pazera does not need to be installed just extract the zip folder then click the mp4toavi.exe file and you are in business. Use ADD FILES from the top black toolbar, select the one you want and then hit CONVERT. Thats it.