If it's public domain then yes it would be ok, but I wouldn't trust copyright information people add as Youtube descriptions.
There are some public domain video archives that might have the kind of material you are describing. At least Prelinger archive material is public domain and legal to use any way you wish.
This is a "sound design" forum. You are asking a LEGAL question. Copyright law is a specialized field and it seems quite possible that there is no appropriate StackExchange forum for this question.
As a general rule, however, using sound or image from another production is almost NEVER something that a competent attorney would recommend. Even if you ...