是否可以使用图形API在视频中标记朋友？

I haven't find anything related. Might be i would have searched wrongly. I want to tag friends in video.

How do i do that using graph api in facebook?

Read this https://developers.facebook.com/docs/reference/api/post/

The post supports adding message tags.

Under the message_tags column

object containing fields whose names are the indexes to where objects are mentioned in the message field; each field in turn is an array containing an object with id, name, offset, and length fields, where length is the length, within the message field, of the object mentioned

It is possible to tag friends in a video, but it's just not in the documentation. I've searched quite some time myself to no avail, but then tried a couple of things and got it working.

The two permissions you need are publish_actions and user_videos.

It works quite similar to tagging photos, which is done with the /{photo_id}/tags endpoint. Although the video equivalent /{video_id}/tags is nowhere to be found in the documenation, it apparently does exist. With photos you can supply the parameter tags as an array. Video tagging only supports one tag at a time with the tag_uid parameter. So if you want to tag multiple people, you'll have to do multiple posts.

This is the final working solution with the PHP SDK:

$facebook = new Facebook(array('[YOUR_APP_ID]', '[YOUR_APP_SECRET]'));

$response = $facebook->api('/me/videos', 'POST', array(
    'access_token' => $facebook->getAccessToken(),
    'title'        => '[YOUR_TITLE]',
    'description'  => '[YOUR_DESCRIPTION]',
    'source'       => '@' . realpath('[PATH_TO_YOUR_VIDEO')
));

$facebook->api('/' . $response['id'] . '/tags', 'POST', array(
    'access_token' => $facebook->getAccessToken(),
    'tag_uid'      => '[FRIENDS_FACEBOOK_ID]'
));