The Latest Social Media Video Specs
Videos that do well on Facebook are generally entertaining or inspiring pieces, for example, customer stories, interesting facts or stunning photographs.

The majority of people watching videos do so with the sound off so to be safe, add captions.
The recommended video size is 1280x720 pixels. Other video formats include:
Carousel video ads: 1080×1080 pixels
Collection video ads: 1200×628 pixels
Slideshow video ads: 1280×720 pixels
Some ideas to post on Facebook:
On your brand's Facebook page, post an inspirational video, employee stories, inspiring or thought-provoking videos.
On your brand's page cover, add a video montage to showcase your business' highlights.
Share short updates, product launches or industry news on your Facebook Stories.

LinkedIn video posts are more likely to be re-shared than a text-based post. The recommended video size is 1920x1080 pixels. Try uploading on your feed positive videos of education or praise of others.

With Twitter, videos can come in various formats but the most common type is self-filmed content talking to camera. These videos are usually short and the recommended size is 1920x1200 pixels or 1200x1920 pixels.
Some ideas you can post on Twitter include:
Tweeting news updates, GIFs or Q&As
Stream live events or behind-the-scenes

Instagram is a highly curated platform therefore the visual content you share should be of optimum quality. In saying that Instagram Stories is a feature that preferences "real life" content which is okay because it disappears after 24 hours.