The above definition is too vague. We should concentrate more on the definition and origin of the world itself, the word includes 'PLACE' as in *placing* something, "I submitted and placed the song onto the album".
Now if a film director comes to me and says "I've heard your work and I want you to work for my film", then that's not a PLACEment, it's a job offer, and the director is my client.
A placement constitutes submitting and placing your work among competitors onto a preferably profit promising project.
You're welcome to further work that out, I wrote that on the spot, I might come back later, gotta go now.