By most calculations, a single HD movie requires 5 Mbps and super HD requires 7 Mbps of download speed.
The average U.S. Internet-connected homes have six connected devices – televisions, desktops, laptops, tablets, smartphones, etc. When those devices are in use at the same time, it’s not difficult to strain the capacity of a 25 Mbps connection, and completely overwhelm a 4 Mbps connection.
Most American homes lack competitive choices for fixed high-speed Internet.
FCC Chairman: More Competition Needed in High-Speed Broadband Market | FCC.gov.