Beta 0.4. If you enter the beach scene section while holding ctrl for skip forward. (In the settings I had skip all text). Somehow it marked Nattan's scene as already viewed when you enter the dvd selection scene (make sure to hold ctrl through into the scene). I then released ctrl and clicked on Julie's scene and skipped through Julie's scene (hold ctrl). When I got back to the DVD Beach Menu Aki's scene got locked automatically even though I didn't click/see it. Although this could be some issue with where I place the mouse cursor or something odd with the touchscreen laptop I'm on autoselecting a scene since I can't reproduce it.
Although in the grand scheme of things skipping it was what I wanted to do so not much lost.
Right this is a strange one. Nattan's PV is the first that is played before the other options are given so after this concludes the option for her disc should be greyed out. What I have noticed though that using both 'ctrl' (manual skip) and 'tab' (auto skip) on the screen that shows the DVDs will cause them to lose their darkened (selected) state although you will not be able to re watch those scenes.
I'll get this flagged so we can look at it further, hopefully get it corrected in the next build.
Be warned, elements of this post may have been influenced by my 'West Country Logic'.