watching dvd w subwoofer

I want to connect a subwoofer to my TV or dvd player to watch dvds. Which do I connect to? Is there a difference?
Unless your DVD has 5/1 analog out, you will have to run it from an LFE out from an HT Receiver.
Yes, you really need an AV receiver that has 5.1 to 7.1 Dolby surround processing. The preferred method is to use the digital coaxial or optical output on the DVD player into the corresponding digital input on the surround receiver. Then the speaker outputs of the receiver are connected to the proper speaker channels -- the subwoofer output is usually an RCA connector because most users have powered subwoofers. Most people do not use the DVD player's analog outputs (needed for SACD playback) because it entails a lot of extra audio cables.

If you don't have a surround receiver you can connect the DVD's stereo analog outputs to your tv's audio inputs, but you can't use the subwoofer that way... But if you happen to have a stereo preamp with two pairs of stereo outputs lying around, you can connect the DVD player's stereo outputs to the preamp's AUX input then the preamp main outputs to the tv with the second pair of pre-outs going to a powered subwoofer. That way, you could use the preamp as a universal volume control to control the volume of the tv and the sub simultaneously. This setup could work okay if the tv speakers are decent (especially if the preamp has remote volume control). And you could always add a stereo power amp and better main speakers down the line. But once you try a full 5.1 channel surround system, there's no going back...

Merry Christmas!
If you connect the sub to the DVD player, you will not be able to control the sub's volume unless the player has it's own volume control
my tv has a subwoofer jack, manual says I can use a mono cable to the sub. Can I do this just to watch TV?
Yes, you can.
mt tv has 1 input jack, but sub has 2 input and output. why does sub have 2 (left and right?)