One of the key acting techniques used particularly in early work is the 2 chairs [can be more than 2 according to the number of players].
This popular technique puts actor first - with limited props and no set [sometimes green screen might be employed].
Apart from the obvious simplicity of planning and set design, it puts the actors and their acting centre stage.
If it's a solo performance we use one chair unless they jump between two as part of the performance. Some license may also be given for costume and historic factual accuracy in performances where special dress limitations and facts might otherwise limit a performance.
When standing up they don't even need chairs - but the principle remains.
Each of these example video's have the common theme of simplicity - The Wimp That Roared has just enough costume to get the storyline - Love Island really needed no special setup apart from a mike some juggling balls and sea soundtrack.
"Kevin" asks you to believe Sonny in an autistic 8 year old and James is his father - actually became his brother in later scenes and always became wet!! Blitz has just an added background soundtrack to add atmosphere.
All were improvised by the actors on a given scenario directed by William David.