Is it possible to get the video title using the video ID with API v3 without the API key? I could not find any information or example of getting the title in the API documentation.
To get the video title, you will need an API key, and you'll need to make a request to:
https://www.googleapis.com/youtube/v3/videos?part=snippet&id={COMMA_DELIMITED_LIST_OF_IDS}&key={YOUR_API_KEY}
In the returned packet, the title will be at items.snippet.title
You can't retrieve any API data without an API key; all API requests are on a quota system, and the key is used to determine how much to charge your app's daily limit. A call like the above, however, is quite inexpensive; it's a total of 3 units (2 for the snippet and 1 for the request itself). Since you get 50,000,000 units a day and can retrieve up to 50 snippets for that same 3 units, it's not much of a burden to use the API key.