The MMR (multimedia redirection) feature enables full-fidelity playback on Windows XP, Windows Vista, Windows 7, and Windows 8 client computers when multimedia files are streamed to a remote desktop.
With MMR, the multimedia stream is processed, that is, decoded, on the Windows client system. The client system plays the media content, thereby offloading the demand on the ESXi host.
For Windows XP and Windows Vista remote desktops, the MMR feature supports the media file formats that the Windows XP or Windows Vista client system supports, because local decoders must exist on the client. File formats include MPEG2, WMV, AVI, and WAV, among others.
For Windows 7 remote desktops and Windows 7 and 8 client systems, the MMR feature supports media formats that comply with the H.264 video compression standard. The M4V, MP4, and MOV file formats are supported.
Windows 8 remote desktops do not support MMR. For these View agents, use Windows media redirection, included with RDP 7 and later.
Because MMR is implemented differently on different operating systems, the system requirements for the Windows 7 operating system are different from the requirements for Windows Vista and earlier operating systems. For information about the system requirements for this feature, see "Using VMware Horizon Client for Windows," available at https://www.vmware.com/support/viewclients/doc/viewclients_pubs.html.
You must add the MMR port as an exception to your firewall software. The default port for MMR is 9427.