Hi @OCX,
The WP plugin should generate a KS with sview privileges [see https://knowledge.kaltura.com/kalturas-api-authentication-and-security] and set that KS in the embed code.
Therefore, provided you set up an access control profile that requires a valid KS in order to view/play the entry, it should work. i,e: embed codes generated by the WP plugin would allow viewing/playback and an attempt to view/play the entry when no valid KS is passed would fail.
Of course, you should test that to ensure it is set up correctly.
That’s entirely up to you, of course:) If you wish to use the WP plugin, you’re welcome to do so.
As you can see here https://github.com/kaltura/all-in-one-video-pack.wordpress/blob/master/readme.txt#L7, it’s FOSS, licensed under GPLv2.