Here is a rig that lets you capture overhead video with your smartphone like a pro. The Glide Gear OH 200 has a modular, adjustable design and comes with multiple 1/4 and 3/8 mounting options. Its height can be adjusted with 26 to 36 inches. You can also add more 15mm rail sections.
The OH200 ships with phone and tablet mounts. It can be assembled and disassembled easily.