You should be getting video straight through from the PS3. Let's start with the obvious things to check. You're switching the soundbar to its BD/DVD input? You're switching your TV to the HDMI input? Have you tried a different HDMI cable between the soundbar and TV? Since the PS3 is fine when connected directly to the TV (I assume on the same HDMI input as you used for the soundbar), then the problem is NOT with the PS3 or the TV's HDMI input. That leaves the cable, the HDMI out port on the bar, or the aforementioned input selection. Do you have another component with HDMI-out that you can try connecting? If the bar has a bad output, you should return it.
When you connect the PS3 directly to the TV, the bar will only get 2 ch. stereo input rather than DD or DTS. Whether that makes a big difference to you, I can't say.
When you connect the PS3 directly to the TV, the bar will only get 2 ch. stereo input rather than DD or DTS. Whether that makes a big difference to you, I can't say.