Cannot upload MP4 file in contact for 7

I have created an entry form with contact form 7 that I require users to upload a picture and a video.

I have specified filetype=jpg and filesize=250 kb for the picture and this is working fine.

I have specified filetype=MP4 and filesize=20 mb for the video.

When I try to submit with the MP4 of 10 mb it just spins and eventually timesout.

Any suggestions?

Thanks for you help.