1) "Undergo treatment" is a valid expression. Something didn't quite sound right, and I think it's the "suddenly" adverb. Undergo has an undertone of a process, long/hard/painful/tedious... and "suddenly" is an unexpected word to see next to it. Grammatically correct, but semantically weird. 2) Grammatically I can't find any obvious errors but it doesn't flow very well in terms of semantics and tenses: - First, I would say "This video aims to....". The passive voice there is not needed and doesn't add anything. - Then I would rephrase the last sentence using "would" instead of "will" (since you're establishing a hypothetical scenario), replace irrelevant for 'unnecessary', remove "suddenly" as explained above, remove the sub-clause between commas, and put it in the subjunctive tense: "rather, we raise a fair (interesting?) question: what would happen to a healthy individual if he were to undergo an intensive but unnecessary treatment?"

1/ Is the phrase "undergo treatment" relevant ? This phrase is relevant and correct for this context. In American English you will hear the phrase "undergo treatment" often to describe a doctor treating an illness. Though, this language feels a little stiff.. I would phrase it like: "What will happen to a healthy individual if he or she suddenly receives intensive and irrelevant treatment for (insert illness here)?" 2/ Do you think the whole text is grammatically correct? From American English: I can understand the passage and the meaning of the passage. Some of the wording does feel a little unnatural, but it is grammatically comprehensible. Example Original: We are not giving answers(because there couldn't be any), but we rather raise a fair question: Proposed Changed: We are not providing answers, because there aren't any, but rather we raise a fair question: ~ I hope that helps!