If there is a specific video or post that you wish to make a draft again, the workaround for this is to change the publish time.
Click the Posts in the upper right corner of your event page to find your posts.
Hover your cursor over the post you wish to hide. Click the gearwheel icon that appears in the upper right corner of the post, then click Edit.
At the bottom of the edit panel, there is a Post Date section with a date and time written.
Click the date and time and adjust them to be in the distant future.
When you're done, click Update. Your post will appear under Draft & Pending Posts and will not be visible to anyone other than you.
Note: The post will automatically become public on the date and time that you specified. If you want to keep the post in draft mode, be sure to update your post as needed before that time.