When you publish a video, the Details screen lets you choose whether it appears from your own account or from a page you run. A post published as a page shows the page's name and photo, not yours.
Steps
Record or upload a video as usual, then tap Next on each screen until you reach Details. On the Trim screen the button reads Next: Add Text.
At the top of Details, under Posting as, tap the row that shows your account.
Choose your own account, or one of your pages under Your Pages.
Fill in the rest of the details, including a Category, and tap Publish.
Good to know
The Posting as row only appears if you run a page that is not hidden. If you have no pages, the post goes out from your account and there is nothing to choose.
Every post starts from your own account. Choosing a page applies to that post only. The next video you make starts from your account again, even right after you post as a page.
In the feed, a page post shows the page's photo and name. On the post screen it shows the page's name. Tapping the name opens the page's profile. The + Follow button in the feed follows the page.
Page posts appear on the page's profile, not on your own profile.
Your account still owns the post, and moderation still sees you.
Who a post is published as can only be chosen before publishing. A published post cannot be moved between your account and a page.
Ripples and Drops cannot be posted as a page, so the choice does not appear for them.
Category, who can see the post and an Originator claim all work the same as on your own posts. For a page post, Followers means people who follow the page. See Who can see your post.
If you are removed from the page before you tap Publish, the app shows Something went wrong. Tap Retry, choose your own account under Posting as, then tap Publish again.