Can you play 3D movies from a USB drive?

What you are asking for is that the 3D HDTV manufactuer also make models that essentialy have all the features of a built in several hundred dollar FHD 3D blu-ray player except that the actual optical drive would be in any enclosure connected with a UsB interface.
I do not think any of the 3D HDTV manufactures will ever produce more espensive models with this additional functionality which is not included now. It makes much more sense for the user to have a separate FHD 3D Blu-ray player which is what the current models support.

A 3DTV shows two images while an HDTV only shows a single image

The 3DTV does all the work, not the 3D BD player.


I'll leave this for someone else to address.

We just don't know these things at this point. I suspect that 3D content, if it's available on a flash drive, will play like content straight from a disc. This happens now, for instance, when you take an SDHC card out of an AVCHD camcorder, put it in an adapter and plug it into a USB port on a Playstation 3. That's how I watch footage I've shot on my Canon HiDef camcorder. I imagine we'll see lots of 3D HDTVs that can read 3D data directly from memory cards plugged into their USB ports. I expect a similar ability to show images from 3D video and still cameras. That's conjecture, of course, but it makes perfect sense. Current first generation sets may not be able to do it. That's always an issue with new technologies. Later models will have more features and will cost less.

The 3D BD player is just able to read that 1920x2205 frame that a regular BD player won't.

When I saw the Samsung short 3D demo last week at Best Buy, the guy said it was coming off of a flash drive since they didn't have their Blu-ray player hooked up yet----I didn't ask if was USB. Also, the short 3D demo looked very good.

I don't see why not, If anything they may need a new codec to run it. If the tv won't run it off a flash drive I bet a PS3 would or a pc hooked into the tv.

If you want to watch a Full HD 1080p per eye 3D film recorded using the new Blu-Ray 3D standards then you must use a 3D player that will decompress and decode the h.264 encioded disk and output it using the 2 frames packed buffer video format to a 3D TV which will then display it using frame sequential format and will support Active Shutter gales from using an IR emitter.
There are many other forms of 3D some of which are recorded on DVDs or standard BR disks and tranmitted in 2D format to 2D TVs.
I really have no idea what short 3D demo the BB store was showing off of a flash drive.

There is no issue with playing 3D movies from other types of media (eg. flash drive)
Generally the image will play as a spit screen until you press the 3D button on your TV controller (most Panasonic/LG and Samsung models). In short, if the media is formatted for 3D, it really doesn't matter how it is delivered to the TV.