It is fine to link to a YouTube video provided you are not linking to infringing content. You can also use the YouTube embed code. The YouTube terms of use allow for these uses without needing permission from the copyright owners. But you will want to be reasonably sure that the videos were uploaded legitimately.
In which case, you should check the uploader's name and the YouTube channel (if there is one), and consider the following:
- Do all the videos on the channel have the same branding?
- Does the uploader's name match the producer's/company's name?
- If you check the URL of the YouTube channel, is the URL a professional sounding name?
- Is the YouTube channel an official channel? It should have a tick against the name.
- Read the description of the YouTube video. Does it appear to be an original video? Most times, educational videos are okay to link to.
- Does the channel have many subscribers? If it a well-known company, there should be a substantial number of subscribers.
Not all the above factors will be present for all kinds of videos, but they're a good starting place. Again, you just need to feel reasonably sure that the video was uploaded legitimately - significant research is not needed. There are some very good fake accounts out there, just like there are with phishing emails, but by considering names, URLs, other content on those channels, and YouTube verification, any non-legitimate videos and/or channels should be weeded out.
Also, when linking to a YouTube video it is best practice to ensure the video opens in a new window.