Right after the 2020 election was called for Joe Biden, there was a video released (on November 7) of Kamala Harris calling Biden and saying "We did it, Joe!"
https://www.youtube.com/watch?v=H3lpFE19T78
In July 2024, Harris made a public appearance in which Biden supposedly called in live (some people think it was an AI voice) over the phone:
https://www.youtube.com/watch?v=VPp5I0j9GBM
Also in July 2024, there was a video of Kamala Harris being called over the phone by the Obamas to announce that they were endorsing her:
https://www.youtube.com/watch?v=Rt0jHTUg0RI
Now there's a new video of her calling Tim Walz to tell him that she has picked him as her running mate:
https://www.youtube.com/watch?v=G-DZg7QXGCs
All of these instances are obviously staged. I also seem to vaguely recall one or two other similar staged calls with Kamala Harris (I think one was between her and a celebrity).
[EDIT: Thanks to u/winn in the moments below, I found out that the call with a celebrity that I vaguely remembered was this one with Taraji P. Henson:
https://www.youtube.com/watch?v=F5pnNZ9bM14
And thanks to u/AllMostThere, I found out about this incident I'd never heard before:
Why? I don't recall any other politician participating in so many clearly staged, filmed phone calls. Why does Kamala Harris do it so much? It's like a trademark for her at this point.
How? There are cameras in both locations, capturing both sides of the conversation. There's no possible way for that not to be set up in advance.