Interesting video in my view only to show how clubs only think about transfer fee - whether it is valuation and fair market value or generating needed revenue. Otherwise nothing noteworthy about player himself, sporting reasons or any other - just money...and that's simply business. In football, it operates under a near monopoly setting in terms of legal oversights on contracts
Now in most lines of work, even under contract, you can negotiate with another company and head for the exit provided you respect the terms of termination in your contract - notice period & bonuses etc, while in football its defined primarily by a certain fee. A fee which is not always about the true valuation or market value but perceived threshold to avert the state clubs easily depositing a bag of money on a whim
In Eriksen's case, club has right to hold him to an objective fee but that number should be aligned up front or in contract else club's can easily overstep their position and exploits the player for money
A handshake or an implied exception to terms of a contract are too complex to leave to chance - define as part of the contract risk being left to the honor of the parties involved