MP4 Video Uploading to WP no longer as standard?

Hello World,

I was just wondering what the workaround was or what settings to update so that I can upload MP4 to WP please? I go to WP Dash> Media > Add Media > Select the media> returned with the error message below.

Since the core update to 4.9, this is the message I get...

“756913811.mp4” has failed to upload.
Sorry, this file type is not permitted for security reasons.

With that in mind, I must need to do something...

Advice appreciated in advance, thanks