he current 2.4GHz wireless technology is sufficient to transfer the video data from a HD camera. Additionally, comparing with 5GHz, the 2.4GHz has better wireless signal coverage.
2.4GHz: 70m (indoor), 250m (outdoor)
5GHz: 35m (indoor)
60Ghz: 15m (RF Beamforming, indoor)
By the way, 95% Wi-Fi cameras in the market can not support 5GHz frequency band.