Not working. AND the exercise shows NOT to include the period BUT the video shows including the period?? All the exercises have worked up to this exercise.
The videos are not a supreme authority. The challenges change slightly over time and people do not make new videos every time that a challenge changes slightly.
That’s really not contributing to the solution, but ok.
When the challenge and the video are not the same, follow the challenge instructions. In this case, the period should not be inside the strong tag.
if you are asking what else could be the issue
it is much easier to debug if you post your code (maybe next time use the Ask for help button!)
do you have any extra space inside the strong tags? something like this is impossible to see from the screenshot, this is a reason for which posting your code make simple to find errors