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I would say it depends on whether you know anything about the particular series you are watching.
With your example, even though it is a few years old, the ES2015 Crash Course is still full of great information worth watching especially if you don't know much about JavaScript.
However, watching Laravel From Scratch 5.0 (still popular) might not help you as much in learning Laravel when the current release is 5.7 unless you are working on legacy Laravel projects.
So I guess it depends on what you are wanting to learn and why, as to whether you should watch older series/videos or not.
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