There probably won't be any options labeled "HD" per say, you'll want to look for the resolution options (labeled like 1440x900, 1024x768, etc). I usually recommend choosing one as close to your desktops resolution as possible, and finding a "keep aspect ratio" option if possible. In any case, keep in mind that there is only so much image data available in these games, and simply stretching the image to a higher resolution won't necessarily make it look any cleaner. For example, take a small image (like 100x100 in size) and zoom in until it's covering your screen; you'll notice the edges get blurry or jagged.
I know with ePSXe the OpenGL2 plugin is supposed to let you use extra shader files to make some games look better, but honestly I've never seen a huge difference using these. Someone else here might have more info on using them though.
"I think that the problem with this video is it is highly derivative of many popular bands within the genre. Although when viewed on its own merits, it does have a deeper groove. However what it has in groove, it lacks in originality. One can't help but be reminded of such bands as Pearl Jam, White Zombie, Suicidal Tendencies and other bands that bear the mantle of so called "Alternative Rock". One is even reminded of Lorie Anderson when she wore curlers. Hehehmhm! This video speaks less to the heart and more to the sphincter. In closing, I think Korn would do well to learn more from -"