I want to send a large video file from my Iphone to people via E-mail

You may use Mail Drop, an iCloud feature.

Use Mail Drop for large attachments

If you want to use Mail Drop to deliver large attachments, make sure it’s selected in iCloud Mail preferences.

1. In iCloud Mail, click the Action pop-up menu in the sidebar, then choose Preferences.
2. Click Composing, then select “Use Mail Drop when sending large attachments.”
3. Click Done.

To send a video directly from your iPhone, check out this article: http://osxdaily.com/2016/01/20/use-mail-drop-ios-send-large-files/

Note that the file cannot be over 5GB in size.

Check out this article:

iCloud: Add an attachment to an email