When you change the o-rings, I would recommend removing the entire oil filter housing for two reasons. One is because it is a lot easier to access the two ports with it off of the engine. The second reason is because then you can also replace the oil filter housing gasket which is probably also on it's way to becoming a problem.
Removing the housing is not too difficult and only involves renmoving the alternator, and dropping the power steering pump down out of the way. After that, there are only six bolts holding the filter housing to the block.
Here are some pictures of what is likely leaking on your car:
You can see the two ports on the back with the plugs in place. The upper port is what your red arrows are pointing to.
Once the retaining rings are removed, the plugs can be drawn out of the ports. Here's what it looks like with them removed:
Here is the underside of the housing that fits to the block. I also show the plugs, o-rings, retaining rings, and filter housing gasket laid out in front:
Here is a close-up of the plug, o-ring, and retaining ring:
Hope this helps out.