Watching a video on your phone is pretty easy on both iOS and Android.
First off - you need to install a video player app that can handle various video formats. Head over to the AppStore og Google Play and install VLC Player. It'll play all kinds of video/audio files.
Then, head over to the Filemail download page. You will be asked to install/open the Filemail App. After opening the Filemail App - then click on the SAVE icon in order to save the video file(s) to your device.
After the video file has been saved - OPEN it in VLC Player (from the Filemail App).