Both Avid and After Effects will import PNG files sequentially and make a clip with a transparent background.  When you output your animation from Poser choose Image Files rather than AVI files.  Poser will output numbered PNG files and you'll end up with a folder with PNG images numbered sequentially.

When you import into Avid or After Effects, you import as a sequence and the system will automatically created a clip using each PNG as a single frame in the sequence.  This clip has a transparent background.

Your problem my be you using a low end editing program that doesn't support Alpha channels.

There is no need to go the greenscreen route in AfterEffects as the transparent clips self key and save a lot of time.  It's especially effective when you use motion blur - no green fringing, the transparency is perfectly preserved.

What did you have to do to fix the library problem?

Looks like this is a Poser 7 problem.  I sent my animated pose walk file to the vendor, Simon3D and he says it works fine on his Poser 8 - the feet stay attached.

He resaved my file and sent it back to me and the feet don't work right when I apply it.

I'm going to upgrade to Poser Pro 2010, I'm tired of fooling around with this.

Well, I contacted the vendor Simon Schild at Simon3D and he was very helpful, sending me a new file (one of the finger digits didn't have a dial in the parameters) and making some suggestions.  He said to turn Limits on and that solved most of the problems.  I can now copy and paste the walk cycle and the feet remain on the ground - no more drifting or dipping below ground.

However, when I made an animation file and stored it as a pose, when I applied it to the figure the feet came off again.  Oh, well, at least the copy and paste lets me get where I need to for now.

Simon mentioned that it might be a problem with Poser 7.  All I got, so I'll never know.

Thanks Dr. Geep, it worked like a charm.

I checked a sequence where I copied the walk cycle and pasted it on into the animation chart.  I then checked the parameters and although the numbers are exactly the same, the legs are in a different position in each new past on.  I don't see how this is possible, but there it is.

If I click from the orginal frame to the new pasted on frame, the parameters are the same but the legs move, twisting slightly and not setting flat on the ground.  The next pasted cycle has even more distortion.  The hips and the top of the body, arms and all, stay in exactly the right postion, it's just the legs.

Since I can't use the walk cycle I added to the library due to the wandering foot problem and I have to make this robot walk into a room, it looks like I'm out of luck unless I want to tweek each cycle - a long, ugly process.  I end the spline at the end of each cycle.  I would think a copy and paste would give me exactly the same motion each time, but it doesn't.

Well, my problems continue.  I spent a good part of the evening animating a nice walk for the robot on my own, figuring Walk Designer might be the problem.  I got the walk right where I wanted it.

Two problems developed.  When I copied the walk (37 frames) and pasted into the animation timeline, everything worked, except the left foot dipped below the ground on every pasted cycle, but not on the original.

So I made a walk animation for my pose library, stared a new project, brought Fat Bob in and applied the walking animation pose.  The right foot is off the joint and about a scale foot in front of the leg.  It moves, but it's not attached.  I'm about to lose it here!

By the way, I managed to apply IK to the legs and arms and it worked great.

lesbently I'm a newbee and not very technical.  How do I apply the script you kindly provided?

IK is grayed out with this figure so I guess it doesn't apply.