How do I film this?

Hire professional film photographer.

You can still use your phone. You'd just have to film the scene again from your POV.

Other than that, you'll need another video camera. If this is going to be a one-time deal, you can borrow someone's phone or camera. If this is going to be an on-going project, consider buying another phone or better yet, get two camcorders. Camcorders will provide you with vastly superior image quality and with the option to use external mics. With your phone, you'll have to use an external audio recorder since the mic in smartphones are even worse than the $8 cameras within them.

Using two camcorders of the same make and model also means that the image quality will be equal and so you won't have the video look different between the various cuts and edits. No digital camera at any price can compare to the image quality, features and ease of use (work flow speed) of a camcorder.

Do it Hollywood style. Shoot the whole thing from the tripod then shoot again with the phone above your desk. Edit the video in the computer.

duct tape and your forehead.

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And there are a half dozen others with up to 1080p