Cell carriers generally solve this problem by paying building owners tens of thousands of dollars a year.
I thought the extent of their antenna technology was just a board with a bunch of token antenna element that gave the illusion that each subscriber was using a dedicated antenna.
It's not like it's crazy hard to make a small digital antenna, so I'm not sure why it would be in doubt that they did so.
Wireless ISPs have been tried for 15 years, but the only place they've been successful is where there is no real alternative. Weather, humidity, and trees make it extremely difficult to compete with the bandwidth and reliability of wired Internet.
Personally, I'm dubious that the Aereo antenna technologies apply to this new venture. The Aereo arrays tuned in relatively low-frequency signals from optimum locations. A wireless consumer ISP using unlicensed spectrum will be the opposite: listening for high frequencies in bad locations.
From the video, it appears that their goal is to have a few transmission towers in a region and then neighborhood or block-level repeaters that receive the signal and rebroadcast it.
So, fixed millimeter microwave wireless from the repeaters to the main gateway, but what will they use from the repeater to the customer?
Some WISP's are starting to roll out 4G hotspots over unlicensed frequencies. That would work in this situation and their experience with micro-antennas could let them cram several antennas into their router to connect to as many of the relays as possible to increase bandwidth and resilience.