Hi Hector
The HDMI output of the HD Extreme 2 is a fully fledged HDMI output, for the full information please check the technical specification here:
https://www.blackmagic-design.com/products/hd/techspecs/
The HDLink is able to convert the SDI output of the HD Extreme 2 into a DVI or HDMI output (using an adapter) for use with computer LCD screens. If your screen already excepts HDMI input, then you can just go directly out of the Decklink card via HDMI into your screen, as long as it supports the appropriate resolutions (1080i, 720p etc)
So to connect to a HDMI monitor or TV is a great solution, especially to use a cheap HDTV as a HD Monitoring solution!
Callum McLay
Technical Support Consultant
Blackmagic Design EMEA