The limitation is done at the Registered Application level. The 10,000 queries per day is really 10,000 units per day
and depending on the methods your using and the number of times you use the particular methods the cost can vary. Each user of the application does not get 10,000 units. The users share a pool of 10,000 per day. You need to come up with a math formula based on the different methods you use, and the number of times you use them per day on average and sum them up to figure out how many credits you need and if 10,000 credits will be enough.
Google calculates your quota usage by assigning a cost to each API method request.
Different types of operations have different quota costs.
For example:
- A read operation that retrieves a list of resources -- channels, videos, playlists -- usually costs 1 unit.
- A write operation that creates, updates, or deletes a resource usually has costs 50 units.
- A search request costs 100 units.
- A video upload costs 1600 units.
See this link for a complete table of available API methods and the associated cost: https://developers.google.com/youtube/v3/determine_quota_cost
After you complete your formula and sum up the number of units you need per day, if it exceeds 10,000 you can make a request to get an extension and increased quota https://support.google.com/youtube/contact/yt_api_form