Are you unable to share a Messenger video on your iPhone to social media, like Facebook? This share feature is not available on the smartphone. But it is possible on your desktop or laptop.
This is for any device using Messenger and Facebook
Messenger on iPhone
On your iPhone, open Messenger and find the video you want to share like the example below:

You can click the Up Arrow rectangle box to send the video to certain friends and/or Create a Group. But we want to share the video to Facebook. Following are the steps:
Messenger on Desktop/Laptop
- Open Messenger or Facebook on your desktop/laptop then select Messenger
- Move your mouse next to the Up Arrow rectangle box
- A Reply and More actions will magically appear
- Click on More
- Click on Save to Facebook
Your screen will look like the below image:

- Open Facebook on your Desktop/Laptop
- Go to Home menu option on Facebook
- On the left hand side menu, expand Explore (if necessary) and locate Saved
- Click on Saved and you will see the video as shown below:

- Click on the Share button to share on Facebook
Sometimes the author has blocked a video from being shared. If so, the Share button will not be displayed.
Courtesy Of
This tip is the courtesy of my wife, Dr. Aletha C. Oglesby. You may want to check out her blog on medical topics at Watercress Words-exploring and sharing the HEARTH of health.
I Would Like to Hear from You
Please feel free to leave a comment. I would love hearing from you. Do you have a computer tech question? I will do my best to answer your inquiry. Please mention the app and version that you are using. To help me out, you can send screenshots of your data related to your question.