English speakers learning the word wenn for the first time often find the parallels to “when” helpful at first. But wenn can also mean "if." For example, a German child pleading for something and promising to be good in return can expect to hear:
Wenn das Wörtchen wenn nicht wär, wär mein Vater Millionär.
If the word "if" did not exist, my father would be a millionaire.
This is comparable to the English expression "If wishes were horses, then beggars would ride" and can be translated more idiomatically as "When pigs fly."
While the uses of wenn in German are varied, it is most commonly used in such simple cases as:
Ich habe kein Geld, wenn ich Dinge einkaufe.
I have no money when I buy things.
Caption 40, Deutschkurs in Tübingen: Die Konjunktion "wenn"
The German use of wenn... dann is also parallel to the English “if... then.” We see this in the following example.
aber auch wenn die Zeit noch 'n bisschen schwierig ist,
dann nimmt man sich gern zu Hause 'n bisschen Ablenkung davon...
but even if times are still a bit tough,
then it is nice to have a bit of distraction from that at home...
Captions 7 and 8, Auftrumpfen: Mit Kitsch und Protz
Sometimes wenn really does mean "when":
und der, wenn er wild wird, uns Sand in die Augen weht
and the one that, when it becomes wild, blows sand into our eyes
Caption 17, Piggeldy und Frederick: Der Wind
So now you see that that Wenn das Wörtchen wenn nicht wär, there would be quite a few things you'd have trouble expressing!
When going through your videos, pay particular attention to a specific aspect of the language, such as a tense, a part of speech (such as the wenn above) or a tricky bit of vocabulary. And then reward yourself by watching one of the fun episodes to allow your mind to process.