I just use the most updated adobe flash player to play movies online. If I'm watching a DVD, then it's just the windows media player. That does the trick for me. However, mostly I use Microsoft silverlight to run Netflix. In fact when it comes to netflix, you can only use silverlight. I see from the previous post that many of you use the VLC player. I erased it of my computer, but now I will consider re-installing.
I also choose VLC to play my videos. My favorite used to be GOM Player but I couldn't hear the sounds without a speaker so I tried using VLC and was satisfied. The only function that GOM has that VLC doesn't have is about the subtitles where you can adjust to make sure that the subtitle is shown at the same time they are spoken. Another thing about the subtitles, through GOM, you can put the subtitle in the left side, right side, upper side or lower or wherever you desire that will make it much easier to read. There were a few movies that can't be watched through GOM but other than those mentioned, they are both reliable.
I only use VLC as my media player. It's the only media player i trust. I like it because it can play a wide range of video formats and it rarely ever crashes. Also the update is consistent. Although i can't play a 1080p video quality in it but i think it's more because of my laptop than the player itself. Anyways, i think VLC is the leading media player nowadays.
I only use Windows Media player to play movies on my laptop. I have heard a lot of people using VLC but I have not tried it yet. They say it is a good software and way better then Windows Media Player. I may try VLC out and see how it is.
I have been using VLC for the longest time now. It has a very simple interface and it can play whatever format you throw at it. Never had a single problem with VLC ever. Though I think it could use a bit of theme improvements to make the interface more appealing.
Another endorsement for VLC ..Easy to use and plays absolutely any media file. Its my favourite media player followed by KM player which gives a more "cinematic" view or so am convinced.