Yes, sort of - from desktops and Android, not iOS (yet)

PC it is

Thank you Joe. I will try this on my PC then.
 

Chromecast now has 1080p support

http://thenextweb.com/google/2014/09/08/googles-chromecast-gets-1080p-chrome-tab-casting-via-beta-extension/

I think you can get the chromecast addon from here: https://chrome.google.com/webstore/detail/google-cast-beta/dliochdbjfkdbacpmhlcpmleaejidimm?hl=en  I say I think because you really need to run this from the Chrome browser (at least it seems so) and I already have it installed on both the PCs in my house (running Win7).

I just tried TrainMasters TV on my 55" downstairs and it works pretty well.  I have the Tab Casting Quality set to extreme, Tab Casting Mode to enhanced and Resolution to 1280x720 and I do notice the resolution is not as sharp as a normal HD broadcast; there also appears to be a minor lag in the synch of dialog and lip movement.  This I suspect could be either due to my settings or to perhaps pushing my wife's laptop a bit too hard.

When you click on the Google Cast icon in the upper right corner of the screen you get a drop down menu with highlighted text to "Cast this tab to..." with the Beta indicator in bright red.  Below that is an Options selection that will let you tweak the settings I mentioned above.  Also note that off to the right of the Beta flag there is a faint box with a down pointing carat in it; click on that and you will see an option to "Cast the entire screen" which is an experimental feature (works well for me).  If you choose that you will be able to cast your entire desktop to your TV making it essentially a duplicate of your PC display.

Good luck and enjoy!

Another key is Vimeo support

I modified my post; see above.

Added a bit more info from my playing with Chromecast and TMTV.

Any chance of TMTV by Roku?

Is there a way to access TMTV by Roku?

TMTV by Roku

I have been able to play TMTV on Roku using my iPhone and the AirPlay channel.  I found instructions for installing an AirPlay channel on my Roku at this web site:

http://www.thestreamingadvisor.com/2014/01/28/how-you-can-get-airplay-on-a-roku-via-the-trimeplay-private-channel-watch-tv-shows-and-movies-from-any-airplay-compatible-site/

Thank you Dan!

This method of adding the channel to the Roku worked great. You have to follow instructions carefully about adding your MAC ID to Roku (so it limits ease of using multiple devices, e.g. iPhone and iPad). It was a bit finicky in terms of the touch screen on my iPad, but once it was started, it worked terrific.

Casting from the Tab

Just a note for those experimenting with the Chromecast.

The video quality varies when you are using the google cast feature from a tab.  I depends on your router and your PC (and the other activity on your home network.)

In my office, I have a relatively robust laptop that is connected directly to the router/wap with a cable.  The Chromecast in that room is, of course wi-fi.  That combination gives great results.  Switching the laptop to communicate via wi-fi instead of the dedicated wire does decrease the quality but it's still not too bad.

In the family room, I use a relatively inexpensive Chromebook and a second Chromecast, both communicating via wi-fi. The quality isn't horrible, but the video can stutter or lag behind the sound at times.  It seems the chromecast or the browser is analyzing the load and decreasing the frame rate when it get's bogged down. Sound is prioritized over video, so the sound is always good. If you don't mind the stuttering video it's often acceptable.  Depends on the content.

When you're using wi-fi for all of the connections, the computer simultaneously receives the streamed video, display it on the computer screen and re-sends it to the network.  That's a lot of work for some older and even newer less capable computers.

So, experiment a bit, if your computer is near your router, try connecting with a cable instead of wi-fi, you'll probably have better results.

As with so many other things in Life - it depends...

As Joe mentioned in a previous post, when Vimeo gets Chromecast support, quality will likely improve over the tab option.  When that happens, the computer hands off control to Vimeo and the video is sent directly to the Chromecast without the trip through your computer.

gs