Form file upload to featured video post without gravity forms?

Im using VideoBox theme.

Is there a script or a free plugin (or workaround) that will allow a form to upload a video file into the featured video of a new post. the best ive gotten to work is to add the featured image, but cant seem to get the featured video added.

Many of the free plugins dont allow video upload, only with premium upgrade.
At the moment, the suggested solution is to use a gravity form, but at the moment its too expensive for me.

It would be good if there was a plugin that did this automatically.