Would it be useful to add method like:
```python
def use_video(video_display_name):
  self.video_display_name = video_display_name
```
and use it so:
```python
self.use_video('A')
self.show_captions() # it means: show captions of video `A`
... # All manipulations with video `A` goes here
self.use_video('B') # Change reference `A` -> `B`  
self.show_captions() # it means: show captions of video `B`
... # All manipulations with video `B` goes here
```
to avoid adding `video_display_name` to all methods? Does it make sense?