I own Bloodsport on DVD which has 'Dolby Digital Surround'. In general when I watch movies I use the 'Direct mode' setting on my receiver, but for Bloodsport the 'Direct mode' that I always use and am happy with limits all the audio to the frout speakers only with nothing heard in the surrounds. I switched the setting over to: 'Auto Surround' and I noticed that I was now getting sounds from my surround speakers as well instead of having everything frout heavy. When I had the receiver set to the 'Auto Surround' mode I had a look at the display screen on my receiver and there is some text written that says: "PL II". That text is NOT present for the 'Direct mode' only for the 'Auto Surround' mode when playing Bloodsport on DVD.
I will add that bascially everything else that is 5.1/6.1/7.1 Dolby Digital/DTS audio etc sounds exactly the same in 'Direct mode' and in 'Auto Surround' mode. There is no "PL II" text to be found anywhere, I've only ever seen it just now with my Bloodsport DVD played in 'Auto Surround mode.'

So anyway what is PL II? Dolby Pro Logic II

And why am I getting sound from ALL the speakers on 'Auto Surround' mode for Bloodsport with its 'Dolby Digital Surround' track but am getting all the audio only in the frout speakers when played in 'Direct Mode'? The DVD must have a two channel track and therefor plays with two speakers in Direct Mode. When you switch to Auto Surround the receiver uses predetermined codecs, in this case with a two channel source you get Dolby PL II.

Could it have something to do with 'Dolby Digital Surround' audio working differently then 5.1/6.1/7.1 Dolby Digital/DTS audio? Yes