On both of the clips you provided, the ball is directly driven into the ground, so the initial bounce, by rule, does not take away kick-catch or fair-catch protection.
Any Team B (receiving team) play in position to make a catch prior to the "second bounce" must be provided an unimpeded opportunity to complete the catch regardless of whether or not they signal for a fair catch. If a fair-catch is signaled, they may not be contacted after the catch is completed (fair-catch protection). Additionally, the ball may not be advanced once the catch is completed due to the fair-catch signal and the play is dead once possession is gained. There is no restriction on where this signal and catch is made in regards to the restraining line and the receiver being protected.
Once the ball strikes the ground a second time (by rule considered the first bounce if the ball was driven directly into the ground off the tee), any fair-catch or kick-catch protection is gone. If a fair catch signal was given by the Team B (receiving team) at any point during the play, they may not advance the ball from where they may gain possession.
In short:
If you signal fair catch, you are only provided protection if the attempted catch occurs prior to the "second bounce."
If no signal is given, you are still provided an unimpeded opportunity to complete the catch prior to the "second bounce" but may be contacted after this opportunity ends.
After the "second bounce" no protection or unimpeded opportunity is given regardless of signal.
