Three different things get confused here, and the answer is different for each. What you can search, what you can paste, and where comments come from.
Searching
In Videos: Instagram, TikTok and YouTube.
In chat: the same three. Ask and Vamos will also go after YouTube long-form and Facebook Ads.
When the index is short on your topic, the search goes live to fill the gap, which is also why chat reaches further.
Pasting a link
A much wider set.
Instagram, TikTok and YouTube posts and profiles.
Facebook posts and ads.
LinkedIn posts, profiles and company pages.
X.
Any website or article.
Plain text.
What Vamos gets out of it depends on the platform.
From a short-form video on Instagram, TikTok or YouTube you get the caption, the transcript and an analysis of what happens on screen.
From a post on the others you get the text and whatever metadata is public.
From a website you get the page.
Comments
Instagram, TikTok and YouTube.
Comments are where audience questions live. A question your audience actually asked makes better content than a topic you guessed at.
Facebook and Meta ads
Ads are searched live, because ads decay as campaigns stop and a stored copy goes stale in a way organic posts do not. That makes ad research a little slower and less complete than organic research, and it is the reason.
An ad-library search page is not an ad. Open the specific ad and use its link.
What cannot be read
Private accounts. Nothing, on any platform, including your own.
Deleted posts. If it is gone, it is gone, and Vamos will say so rather than guessing.
A profile where you wanted a post. Some actions want one video, not a whole account. Saving to a Collection is one of them, and it will tell you to open a video and use that link instead.
Playlists and channels as single items in a Collection. Individual videos only. A channel link works in a chat.