Adding the AJAX upload method to my website

I have a website that currently uses a HTTP POST code to upload videos and images to my database, I need to change the file size limits for my website so my users can post video files that are 1GB or less. Someone has informed me that the POST HTTP method there is a limit on the max file size that can be uploaded so we need to change this to upload method AJAX or something that works where we do not have any file size limitations for uploading files to our website. Also we need to make sure that uploads are successfull 100% of the time we dont want it where someone has a slow interenet speed but our website does not allow them to upload big files. The other part of the work is I need someone to add a upload bar to the pages where any videos or images and media are being uploaded so that users know the progress of the upload.