It depends on just which way you want to do things. Here are some ideas that may help you do what you want...
If you want to select things from you TV itself, then you can (on the 70b tablet) go to Apps => Media Server. That should allow your 70b to show up on your TV like any other DLNA source, and you should then be able to select what you want with your TV's remote control (like any other DLNA source). [You may want to also select "Keep device awake while service is running", or you could try changing the Wi-fi settings to stay on when the tablet screen blanks out (not sure if that works)]
Be forewarned that the above method may not work very well if you have a microSD card in the tablet with a lot of media files on it. Remember, the 70b has only a single core CPU with limited memory, so it can run out of umph if it has to many files to deal with.
Now, if you would rather select file(s) on the 70b tablet itself to display on a DLNA compatible TV, then you may want to get the iMediaShare app from the Google Play store. Here again, you may want to change the Wi-fi setting to stay on when the screen blanks out. Normally the Wi-fi turns of when the screen blanks which would also cause the DLNA to drop out.
Or, instead of all the complications of using Wi-fi, you could just plug in an HDMI cable (needs mini-HDMI on the tablet end), but... remember, with an HDMI connection the 70b tablet does NOT mirror its screen (the Archos manual is wrong about this for the 70it2, it still works like the older 70it). Instead, the tablet screen blanks out and changes to operate as a "touch controller" type method of operation. Takes a bit of getting used to, but you can do most things with it that way.
Hope this helps you do what you want. The Archos 80 and 101 G9 tablets are better and can handle 1080p HD video, while the 70b can only do 720p (and it is a lot more nit picky about certain video characteristics also).
Archos 101 G9 8G classic (512M RAM)