You'd probably be fine but its just in case you partner later on!
You could be OK for years and suddenly they catch up with you, meaning you'd have a lot of content to change or remove - so best just enquire from the start
![Wink ;) ;)](/styles/default/xenforo/smilies/wink.png)
The music Ive used in my Channel Trailer, for example, was from a trailer for an item by Kingston Tech (the memory manufacturers) - so before using it I got in touch with them (I've done reviews for them recently so have a good relationship with them also) and made sure I got permission that I could use it, and have kept the email stating that they have given me permission etc, just in case I ever need to dig it out in the future!
Never know what could happen!