Let's say you have a set of videos on your hard drive that you want to play on your TV. Maybe they're home videos of your child's soccer team, or maybe you downloaded every single episode of Mad Men via BitTorrent, we're not here to judge.
The point is, you want to watch these videos on the HDTV in your living room, not on the PC in your office. Here's how to do it quickly and easily. Depending on your home theater setup, you'll either directly connect your PC to your TV, stream the videos over your home network, or use your TV's ports to attach a storage device.
Plug your PC directly into the TV
If you have a laptop or a small PC, you can just plug it directly into your TV. That way, you won't have to buy any new equipment (except for a cable or two), you won't need to deal with codec or networking hassles, and you can use whatever applications you like.
The type of connector your TV requires will depend largely on how new the TV is. HDMI is ideal, since you need just one plug for HD video and audio, but you can also use VGA (or DVI) with an inexpensive 3.5mm-to-RCA audio cable.
If your TV doesn't have HDMI or VGA, things get trickier. Your only option for HD video is component video, but not all PC video cards support component output without a converter. You might be able to use an S-Video port (1024x768 resolution), but you're probably better off looking for another option.
Use your TV's USB ports or SD Card slots
Newer TVs typically come with a USB port or an SD Card slot, so you can plug in a USB drive or memory card and view your photos, listen to music and watch movies. Often, however, such features are designed with digital cameras in mind, and they may not always support the file formats and media codecs you need to watch TV. You can find out what formats your TV supports in the specs listing or user manual.
The Sony KDL-55HX800 TV, for example, supports video in AVCHD (a format used heavily in HD camcorders), MP4 and MPEG-1, while the Panasonic TC-P42G25 lists support for only AVCHD and MPEG-2 videos. Odds are, your downloaded videos aren't going to be in those formats; most TV shows are encoded with the x264 or XviD codecs, which you won't find on these TVs.
The Samsung UN40C7000, on the other hand, supports a veritable bonanza of common codecs, including Divx, XviD, MPEG-4 and H.264. But if you're particularly unlucky, you might own a TV that doesn't officially support media playback yet, the Vizio XVT553SV for example has three USB ports but requires a not-yet-released firmware update to support playing media via USB.