Thank you page

I have integrated the form on the contact us page. I am accepting videos from the visitors to the website. the file size submitted by the users is quite large due to that. This slows down the process of sending the video when someone hits the submit button. It appears that there is no action happening when someone submits the form and they think it has not gone through. Also, it takes a very long time for the form to get sent. Is there a solution for this problem?

Many thanks

The page I need help with: [log in to see the link]