Why is it impossible to test everyone? Korea tests the entire population, 3 mil tests per week. China tests the entire population of Wuhan, 11 mil, in 10 days.
The test is only relevant at that point of time when testing.
So testing everyone is also of no use unless you test everyone at the same time and have them all under lockdown until the results are released so as to enable effective containment.
Entire population testing is just not practical and not feasible.
What the lady in the video suggests is a good alternative ie random section community testing/surveillance testing to get an idea as to the status of the virus in the community. Think the authorities have already been doing this amongst other things.
Best advice from this lady is at the end of the video... STAY VIGILANT...this has to be the new normal until there is a vaccine or the virus dies out.