Need to structure the information clearly, separating filmography and popular videos into sections for each actor. Maybe use bullet points or lists for clarity. Also, mention any significant awards or achievements as that adds depth.

For Nayanthara, she made her debut in "Nerukkin Sansar" in 2003. I should list her notable films in Tamil, Telugu, and other languages. Mention her collaborations with top directors like S. Shankar and directors like GVM. Also, note any awards she's won, like Best Actress.

Next, popular videos. Simbu has songs like "Nenjukkule" from "Kedi" and "Azhage Azhage" from "Nenjil" that are popular. Nayanthara's songs like "Ena Enna" from "Kaatrinile" or "Kadhal Rojakku" from "Samarakuthani" come to mind. I should include these and maybe some recent ones from their newer films.

Finally, summarize their careers and contributions briefly at the end to provide a well-rounded overview. Make sure the text is engaging and informative, suitable for a user looking to understand their film histories and popular works.

Wait, but some of these song titles might be outdated. Need to verify the film and song titles to ensure accuracy. Also, check if any of their recent projects have popular music. For example, Nayanthara's "Vikram Vedha" (2017) has some memorable tracks, and Simbu's recent "Bhoomi" (2021) might have trending songs.