Are you watching the JVC as it records? (And therefore NOT watching the actual encoded signal.)
Are you watching the DVD -- after it's recorded, before edited on the computer -- on the JVC or another player?
Are you using the same DVD player or recorder to watch the videos? Remember that the JVC DVD recorder has de-block filters on playback, too -- it's not just on recording!
If another player, does that player have deblock filters? If so, are they on?
Does the HDTV have deblock filters available? Some do, like my nice Sony set. Others do not.
You'll probably be waiting in vain for a high-definition recorder, similar to a DVD recorder. Because of all the greedy studios and anti-piracy zealots, such products may never exist. You'll need to go with a computer route for that, like a Blackmagic card or something higher-end (Matrox, Aja, others).
Download a demo of Womble MPEG Video Wizard, use it. More at
http://www.digitalfaq.com/forum/show...-vcr-1880.html
The only other way to further avoid blocks is lossless/uncompressed AVI capture, with pre-filtering, followed by multi-pass VBR encoding. That takes much longer, and the "better quality" can range from a lot better to not much difference. Consumer sources are just noisy.