To post your video on YouTube:
In the SHARE section, click the YouTube button and follow the instructions. Just make sure you've already signed up for a YouTube account prior to exporting your Animoto video. And, keep in mind that the exporting process can take up to 20-30 minutes to complete.
Alternatively, you can download your video as a MP4 file and upload it directly to YouTube.
Video quality tip: To make your exported YouTube videos a much better quality, add this to the end of the video's YouTube URL:&fmt=18