Compression of files on whatsapp when i try send a vid whatever the size it reduces to 16mb, does the application compress files and to what extent. 
Also how large a file can i send on the application?
https://www.whatsapp.com/faq/en/iphone/20964587

Send an existing video

Tap Choose Existing Video to share a video from your Camera Roll or Photo Albums. You will have the option to preview and add a caption to your video before sending it. Existing videos are limited to 16 Megabytes, or about 90 seconds of video on most phones. If you choose an existing video that is larger than 16 Megabytes, you will have the option to trim the length of the video before sending it. Videos may be automatically compressed to ensure quick delivery.