the 2460 comes with a UVD 2.0 engine, so there is no problem decoding up to 2 1080p videos on the GPU. You can display videos on all 4 monitors. You can find additional information on the video decoding on our web-page:
The uvd engine can decode a 1080p video with no lags.Still you overall playback performance will also depend you other components in you system as well as on the current system load. In general I do not see any problem in playing a1080p video on a 2460 fluently.