Is it possible to get file to upload via ajax?

I am using Amazon S3 (for both original and encoded) and Zencoder. Although everything works fine the UI for this is not great since for "large" files it takes a long time to upload the video and therefore a long time to submit the node form. It is somewhat obvious on a desktop browser that something is going on; but less so on a mobile.

Ideally, the node would submit immediately and the video uploading to Amazon would happen in the background. Is this possible?

Regardless if done this way or the way it is now; the video page is missing the video preview img (since Zencoder hasn't created one yet). To extend this ajaxifying even more; ideally, a replacement img would be shown (can likely do this with simple setup); but then ideally it would be replaced via ajax by the correct img when its available. But this feature is secondary to the form not taking 15 min to submit.