The company should use Amazon S3 for storing and retrieving the videos. Amazon S3 is a highly durable and available object storage service that can handle large quantities of unstructured data, such as videos. It offers scalability to meet the increased storage demands as the number of users grows and has a pricing model that allows for cost optimization, especially with large data sets. Amazon S3 also provides various storage classes that can further reduce costs depending on access patterns, such as S3 Standard-Infrequent Access for less frequently accessed data. On the other hand, the other options either do not primarily focus on object storage (EBS is for block storage, EFS is for file storage) or are not storage services at all (Lambda is a serverless compute service).