External widgets to control media

Hi again, @Goyo!!

I think I found out how to deal with it.

*But an observation first: I edited my code above to be more clear and
look alike the answer I came up with.

The idea I had was to delete the widget every time a button is clicked and update the widget based on this interaction. You can see a discussion about deleting widgets here.

I created a placeholder with st.empty(), and before any update a placeholder.empty() is performed. This made the use of start_time possible for subsequent reruns.

import streamlit as st

data = "video.mp4"

st.write("Click to go to that moment in video.")

time_stamps = [
    (st.button("Part A", "a"), 1),  # bool, moment (seconds)
    (st.button("Part B", "b"), 20),
    (st.button("Part C", "c"), 40),

placeholder = st.empty()

time_chosen = [v for k, v in time_stamps if k == True]  # return [int] associated with a clicked button
if time_chosen:
    placeholder.video(data, start_time=time_chosen[0])