You can use search operators to remove phrases or sites. For example, to have search results display without the word MP4 in the results, use the search phrase
To exclude a site such as facebook, use the search phrase
A combination of these can help to narrow your search results based on what you need.
Exclude words from your search
Put - in front of a word you want to leave out. For example, jaguar speed -car
Search for an exact match
Put a word or phrase inside quotes. For example, "tallest building".
Search for wildcards or unknown words
Put a * in your word or phrase where you want to leave a placeholder. For example, "largest * in the world".
Put "OR" between each search query. For example, marathon OR race.
Search for a specific site
Put "site:" in front of a site or domain. For example, site:youtube.com or site:.gov.
Sources: Google Search Help > Refine web searches