Problem with hardware acceleration on HBO GO

Question

I just got a Zotac ZBOX AD02 (AMD E-350 APU w/ Radeon HD 6310) and in general it's working great.  However, I  have a problem with Flash video on HBO GO.  For the first minute or so  of steaming video, everything seems perfect.  Video is high quality and  smooth, CPU is around 50%.  Then after a minute or two there will always  be some visible video glitch and CPU utilization will jump up to  90-100% and playback becomes extremely choppy.  So I'm guessing Flash  hardware acceleration is working initially, then something happens that  kills the hardware acceleration, and of course the E-350 CPU is not up the  task by itself.
The really strange thing is that it seems to be specific to HBO GO.  I  can stream HD all day long from Amazon Instant Video and Youtube (at least when Youtube is able  to dish it out fast enough).  And it's definitely not a bandwidth  problem.  I have Comcast cable (20Mb down), and a bigger computer I have hooked up  to another TV  has no problem with HBO GO.  I think the same problem happens on the bigger computer, but it's faster CPU can overcome the lack of hardware acceleration.
I've got the latest drivers from AMD and the latest Flash player (even  tried the 11 beta) and have tried all the main browsers (FF, IE, Chrome), but it's always  the same: 1-2 minutes of perfect playback and moderate CPU utilization,  then jacked up CPU and choppy playback.
Unfortunately, there doesn't seem to be any way to contact HBO GO directly about this problem (support links just refer you to your cable provider), so I thought I'd give it a shot here. Is anyone else out there having this problem with HBO GO or any other  Flash video sites?  Any thoughts on what else I could do to track down the  root cause?

Answer 1

Well, my idea with 10.x on IE didn't really work.  Results were not nearly as good as in Firefox, and I'm not willing to use 10.x in my main browser.
However, based on your insight on the wmode=transparent issue, I started playing around with a Greasemonkey script to force wmode=direct, and I think it actually works.  I haven't been able to try it at home yet on the problem PC, but here on my work PC (don't tell anyone I'm not actually working) it makes a massive difference in CPU utilization.  Without the script CPU is around 80-90% during video playback.  When I enable the script it drops to around 20%.  The only issue is that I usually have to refresh the page once video playback starts to get wmode=direct to take effect (start video playback, then once the video playback page loads, hit refresh in the browser).
My script is just a modified version of this one I found:
http://userscripts.org/scripts/show/67260
Here's my modified Greasemonkey script (hopefully the forum will allow javascript in posts):
// ==UserScript==
// @name           Force flash wmode direct on HBO GO
// @namespace      http://userscripts.org/topics/3090#posts-11620
// @description    Force flash video playback on HBO GO to use wmode direct to allow hardware acceleration
// @include        http://www.hbogo.com/*/video*
// @grant          none
// ==/UserScript==
(function ()
    nodeInserted();
document.addEventListener("DOMNodeInserted", nodeInserted, false);
function nodeInserted()
    for (var objs = document.getElementsByTagName("object"), i = 0, obj; obj = objs[i]; i++)
        if (obj.type == 'application/x-shockwave-flash')
            var skip = false;
            for (var params = obj.getElementsByTagName("param"), j = 0, param; param = params[j]; j++)
                if (param.getAttribute("name") == "wmode")
                    skip = true;
                    param.setAttribute("value", "direct");
                    break;
            if(skip) continue;
            var param = document.createElement("param");
            param.setAttribute("name", "wmode");
            param.setAttribute("value", "direct");
            obj.appendChild(param);