Some HP ProCurve switches have a feature called 'Storm Control' that is turned on by default.
HP's definition of Storm Control:
Storm Control—This feature protects against condition where incoming packets flood the
LAN, causing network performance degradation. The software includes Storm Control
protection for broadcast and multicast traffic (unicast frames are not affected). If the rate of
incoming traffic on an interface increases beyond the threshold (5% of the port speed), the
traffic is dropped.
Storm control must be disabled in order to stream video through the ports properly.
Storm control is located in the 'Advanced Security' section of the ProCurve interface.