Connectivity from iMac to TV via HDMI cable I connected my iMac to my TV via HDMI cable. The desktop background shows up on the TV, but no other content. Oddly, a couple of the items in system preferences show up, but nothing else. How can I see what's on my computer on my TV screen?
On your iMac, click System Preferences > Displays > Arrangement, and check the box that says "Mirror Displays". 

This will essentially mirror your computer's screen to your TV connected through HDMI.