Actually, Winston sponsored  The Flinstones for only the first two seasons. In the third season, when it was decided that Wilma would become pregnant, and have a daughter [girl dolls sell better than boy dolls apparently] Welch's Grape Juice replaced the cigarette brand as primary sponsor.

It is correct that Phillip Morris was the original sponsor of I Love Lucy. It was Hanna/Barbera who created the cartoon versions of Lucy and Ricky who climbed up and down the cigarette package during the opening credits. The closing credits always rolled over a package of the sponsor's product. In later years, this would include Maxwell House coffee and Cheer Laundry Detergent. Because of this, the opening and closing credits were redone with the heart when the series finished production and went to the CBS daytime schedule and later to local stations. I have seen the opening credits of the series premiere on youtube as well as some of the closing credits featuring Cheer detergent.

If you watch those old "sponsored by" shows from the 50s, they used to work the commercials into the actual program. In the case of Burns & Allen, it would be part of the script and the comedy would continue even as the shilling was happening. 

I know it would never happen today because there are very few "brought to you by" shows anymore, but I often wonder if they tried that technique now, would it keep viewers with itchy fingers on their remote controls or DVRs from tuning out the spots? 

It could be worth a try, although it does create problems when it comes to syndication and reruns, when the spots had to be cut out. But I know if they made it part of the program somehow, I wouldn't be as anxious to be flipping or skipping the commercials. 

I have seen some of those Burns & Allen episodes with the Carnation Evaporated Milk [from contented cows] dialogue. Some of those "conversations" would last five or six minutes.

Something I did not know. In its first two seasons, Burns & Allen aired every second Thursday at 8pm. It shared the timeslot with something called Starlight Theatre in 1950-51 and Garry Moore in 1951-52.

That's the thing about B&A. It was, to my knowledge, the first TV show in history to acknowledge that it was a TV show. Ironically, it was about George and Gracie supposedly putting on a real television show, which we never saw. The only thing similar was Green Acres, where characters saw the credits and commented on the "wavy effect" before a flashback or read the occasional subtitles.  

There's one episode where George & Gracie are supposed to be staying at a hotel in New York. It's snowing like crazy outside, but George opens the door to the balcony, looks up in the sky, and yells, "Sidney! Stop the snow! I need to come out and do my monologue."

The snow immediately stops, George does his bit for the camera, then heads inside, while looking up and yelling, "OK, Sidney!" At which points it immediately starts snowing again.

What other show would dare try that? I know "It's Garry Shandling's Show" tried breaking the fourth wall many decades later, but it wasn't nearly the same. This show made an art of it and it always makes me laugh. Every season is available on YouTube, but you should start with the filmed ones. The live kinescopes aren't the best quality, were interrupted by musical numbers and until they put it on film, it wasn't the same show.