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According to this, "new research has found that viewing other people exercise actually increases your heart rate and other physiological measures, just as if you were working out yourself".
This got me thinking, can muscles be developed to be stronger and bigger from simply watching videos of people weightlifting from the point of view of the weightlifter?
That is highly unlikely.
The article to which you linked specifically states:
While watching other people exercise may increase your heart rate and have other physiological effects, nothing can replace the health benefits of getting off the couch.
With proper nutrition, muscle is built through exercise by
adding sarcomeres [to muscle cells which is] physiologically determined by the degree of force a muscle can generate that is in turn dependent on the degree of overlap of the thick and thin filaments. Thus, the amount of tension would control the number of in-series sarcomeres in a single muscle fiber.[1]
Watching a show about cooking might stimulate hunger, but it won't put food into your stomach. Watching something that evokes a sympathetic response (fear, fighting, an attractive person exercising vigorously, an athlete in a competitive event, etc.) will elevate heart rate, sweat production, and resting muscle tension, but there is not enough tension to produce muscle growth.
In addition, there might be small deleterious effects to watching emotionally charged movies which elicit a sympathetic response: they cause stress. An effective horror film will elicit tension and maybe even a startle response - making you jump in your seat - but it will also elevate your blood pressure, etc.
Exercise is good for you physiologically. Simple stress without exercise is much less so.[2]
[1] Muscle growth and exercise
[2] The Physiology of Stress: Cortisol and the Hypothalamic-Pituitary-Adrenal Axis (simplified but relevant)
I doubt it. Muscle growth comes from literally damaging muscle fibres by putting them under too much load. This is what causes the muscle pain after a workout. This triggers thickening and increase in number. Without the damage in the first place, there's no reason for the fibres to change.
