advice to choose instance type

For your specific use case of running a Tor browser to watch videos 24/7 for advertising and marketing video tests, you should consider a cost-effective instance type that balances performance and economy. Given that your workload is not computationally intensive and doesn't require specialized hardware, a general-purpose instance from the T family would likely be suitable.

The T family instances are burstable performance instances, which means they provide a baseline level of CPU performance with the ability to burst above that baseline when needed. This aligns well with your video streaming needs, which typically have consistent but not extremely high resource demands.

Considering your requirement for the cheapest option, you might want to look at the t3.small or t3a.small instance types. These offer a good balance of CPU, memory, and network performance for your use case while being among the most cost-effective options.

Keep in mind that running instances 24/7 can accumulate costs, so you might also want to consider using EC2 Spot Instances if your workload can tolerate interruptions. Spot Instances can offer significant cost savings compared to On-Demand pricing.

However, it's important to note that using AWS resources for continuous video streaming might have implications related to AWS's acceptable use policy, especially if it involves copyrighted content. Ensure that your use case complies with AWS policies and any relevant laws or regulations.

Lastly, remember to monitor your instance's performance and adjust the instance type if needed based on actual usage patterns and requirements.
Sources
Choice instance type | AWS re:Post
How to find out what instance is best for my case? | AWS re:Post