There's a few ways to deal with this.
First, plug the player into a standard 16:9 HDMI TV. If it stretches the image, you need to change the settings in the player to output 4:3 columnboxed video.
If it shows up on-screen on the TV with black columnboxes on the sides (so 4:3) then you need to change the settings in your capture device's Source Properties (right-click it in the Sources list, and input a 4:3 resolution). This may also work if the player is sending a 4:3 signal but your capture device is force-stretching it by default.
If that doesn't work and the source goes black, change it back so you get a signal again. Then right-click the source in the Sources list, go to Transform, then Edit Transform. You can then manually enter a 4:3 aspect ratio to squash the post-capture image back to the right aspect ratio. This is the worst choice though, and will have the most image degradation due to being stretched and then squashed back.
...also, if you didn't tell your Mom that it wasn't the aspect ratio making her look fat, you have failed as her child. Take the slap. It's worth it.
