Many low-to-mid budget Tamil films are officially uploaded by their producers on YouTube, often monetized with ads. Search for "Thenalli full movie" on YouTube and look for channels with verified badges or names like "Thenalli Official," "S. P. Hosimin Movies," or "Santhosh Films."
The story follows Thenali (Kamal Haasan), a Sri Lankan Tamil refugee suffering from extreme Post-Traumatic Stress Disorder (PTSD) and various phobias. His psychiatrist, Dr. Kailash (Jayaram), takes him on a vacation to Ooty to treat him, but Thenali’s eccentric behavior and accidental closeness to Kailash's family—including his sister Janaki (Jyothika)—drive the doctor to the brink of insanity. thenali full movie tamilgun full
Use the search function on each platform. If Thenalli isn't there, request it—many platforms consider user requests for licensing. Many low-to-mid budget Tamil films are officially uploaded