Q: my 2010 macbook pro OS X 10.8.5 will not send video to my Insignia HDTV via mini display port….. HELP

are you selecting mirroring ?

in system preferences/Displays

check show mirroring options etc

and sound on system preferences/sound/Output tab and selecting the TV

see

http://support.apple.com/kb/HT4241

Is the box under that checked see attached

also have you switched to the correct  HDMI port on your TV

Does your TV show in the sound output of your mac

Try a PRAM and SMC Reset

http://support.apple.com/kb/ht1379  for PRAM

http://support.apple.com/kb/ht3964  for SMC

If you have selected and switched to  the correct HDMI ports with your TV Controller

Then try another lead.

see further threads here

https://discussions.apple.com/message/21042936#21042936