You need a broad overview
There are times when you want someone to explain everything to you - beginning to end. Books are very appropriate for this.
Example: An overview of the legal, moral and medical issues surrounding right-to-die

 The topic is very recent
Books take an awfully long time (years!) to get published, purchased and put on library shelves. If the issue you are researching is constantly changing, a book may be outdated by the time it arrives in the library.
Example: The latest information about the parental consent debate for underage abortions

 Your research topic is historical
Books lend themselves to topics in which the facts don't change much over time.
Example: A detailed account of the development of the civil rights movement in the United States

 You have a fairly narrow topic
Sometimes books just cover too much and offer too many perspectives.
Example: The theme of isolation and desperation in Charlotte Perkins Gillman's "The Yellow Wallpaper"

 Your topic requires witnessing real events or situations
Films and videos provide visual records of historical events, cultural practices, or natural phenomena. They allow viewers to witness situations that may be difficult or impossible to experience in real life.
Example: Analysis of delivery techniques used by Martin Luther King Jr. during his "I Have a Dream" speech

 You need credible or scholarly information
While some films and videos like documentaries or educational videos can provide factual information, they do not go through the same rigorous review process and are less reliable.
Example: Impact of social media on mental health

 Your topic includes personal testimonies
Films and videos can feature interviews with experts or individuals who have personal experiences related to your topic. This can provide valuable insights, perspectives, and storytelling elements that enhance your understanding and engagement with the subject.
Example: Impact of climate change on people living in certain areas

 Your topic covers a long time span
When something has a long history, you may only find one aspect covered in a film or video
Example: The impact of Brown vs. Board of Education on the public school system in the US

 Your topic is a comparative analysis of different forms or adaptations of a specific work
Films and videos may be relevant sources if you are comparing a written work with a film adaptation or two films telling the same story from different eras.
Example: Comparison of William Shakespeare's Twelfth Night with the 2006 movie She's the Man

 You are just beginning your research and need to come up with key terms to use for your searches
Web resources can provide helpful, generic background information that you can use to develop your topic and identify more specific keywords or terms for searching library databases.
Example: You need more information on the Black Panthers to determine which aspects to research for your assignment

 You need credible or scholarly information
Since anyone can publish information on the internet, web resources are generally considered unreliable because they do not go through a rigorous review process before being published.
Example: Impact of social media on mental health

 Your topic involves finding different perspectives or how different people respond to societal events or information
Since anyone can publish on the web, especially on social media platforms, web resources can be a good way to collect examples of how specific individuals feel about certain topics.
Example: How people in different societal groups reacted to the COVID-19 pandemic

 Your topic is on a complex issue requiring in-depth information
Since most web resources are not written by scholars or experts in the field, their content is likely to have less depth and analysis and instead provide only a broad overview or understanding of the topic.
Example: Benefits and challenges of establishing universal healthcare in the United States

 You need statistics usually collected by a government agency
The government collects and publicly publishes statistics in many areas including education, socioeconomic data, health, and information on foreign nations, among others.
Example: Variation in unemployment and poverty rates across the United States

 Your topic or assignment will benefit from the usage of multimedia resources
Web resources can include multimedia content, such as videos, images, and interactive tools, which can enhance your research.
Example: A research assignment on the cultural significance of music festivals might benefit from the inclusion of photos, video, or audio recording of such events and the people that attend them