It's easy to understand why companies would want to use frame relay for video.
Frame relay is the most widely deployed data transmission method in the world.
It's also less expensive than ISDN, leased lines or ATM for the bursty kinds of data typical companies network most of the time. The key issue is reliability. Virtually every router can deliver prioritization at the frame level today. SLA guarantees a minimum availability, a minimum amount of delay, and provides other types of service guarantees. These service levels can be monitored.