Is Centurylink "throttling" Youtube ala Netflix/Verizon?

All day today, all Youtube videos have been refusing to play for me on two Centurylink connections. However, they play fine via three other network providers--both direct connect and via VPN.

One laptop has been used on all direct and vpn connections, an Android tablet on each direct connection, and a desktop on one direct and vpn connection. Chrome and Firefox both used. The common denominator is Centurylink.

So the question arises, is Centurylink now following Verizon's lead, and beginning to "throttle" high-bandwidth sites?