Welcome to Android Central! Since iPhones use iMessage, which is not available on non-iOS devices, you'd have to use a different messaging app and ask the recipient to install the same. For example, you could ask the recipient to install Hangouts and send the video that way. Or WhatsApp, or other chat apps (I'm not certain which ones support HD videos). The other alternative is to upload your video to your Google+ Photos and privately share it with the recipient (which is essentially what happens when you send a video via Hangouts), or upload it to YouTube and privately share the link.
The problem with sending it via conventional MMS is that there is a strict filesize limit--usually about 1 MB or less, which is obviously not much if you want to send a video.