If you're a parent waiting patiently for your toddlers to grow a wee bit older before buying them one of those classic Walt Disney animated films you've seen advertised on videocassette, you might want to reconsider.

With Walt Disney Home Video's limited-time-only policy, which removes animated classics from the marketplace after a prescribed time period, your children may hit puberty before the title you want becomes available again - if it becomes available at all.On April 1, Walt Disney Home Video will stop selling two of its most popular animated films on video, "The Little Mermaid" and "Peter Pan." After that, consumers will be able to buy the titles only as long as existing inventories hold out in retail stores and distributor warehouses. Estimates of how long that will be range from six months to two years.

"The Little Mermaid" and "Peter Pan" may become available again on video in five to seven years when Disney re-releases the films theatrically, but the studio's home video division isn't promising it.

"The idea is to create a mystique surrounding a classic title," said Barbara Wexler, editor of Video Software Magazine. "You can't diminish the fact that you're dealing with special titles. You have to pay some respect to them. The reason they're only available for a short period of time is so that they don't turn into run-of-the-mill titles."

"The Little Mermaid," which won critical raves and two Academy Awards for music last year, set a box-office record for animated films, grossing $85 million. Disney deemed it an instant classic, and when the video was released in May, it sold more than 10 million copies to become the top-selling video of 1990.

And "Peter Pan," about the boy who refused to grow up, has shown little signs of age even though it was first released in theaters in 1953. The fantasy grossed $29.4 million in its sixth theatrical re-release in 1989, and has sold 7 million units since coming out on video in September.

Video distributors and retailers acknowledged Disney's foresight in removing its top-selling titles from the marketplace to preserve their evergreen status as theatrical releases. "From a marketing standpoint, Disney has a real advantage: Buy it now because it's not going to be available later," said Tim Shannahan, president of the Sacramento-based V.P.D. Inc., the largest video distributor in California.

But most agreed that the practice befuddles consumers at the retail level.

"You take a Disney classic title, a `Cinderella' for example," Shannahan said. "People know it's been available - they may even have rented it - and then they want to buy it for a gift and can't buy it at retail. The whole thing tends to confuse consumers."

By cutting off sales of "The Little Mermaid" and "Peter Pan," Disney can create demand in the children's video market for "The Jungle Book," which will be released for the first time on video in May.

A "Disappearing Classics" advertising campaign is under way to let consumers know that "The Little Mermaid" and "Peter Pan" won't be around much longer.

Other Disney classics that were once for sale but no longer are available on videocassette are "Robin Hood," "Pinocchio," "Sleeping Beauty" and "Lady and the Tramp." The likelihood of finding those titles in stock at your local video store is akin to stumbling over gold on the ground. "Cinderella," put on moratorium in 1989, is almost as rare. Only "Bambi," taken off the market last year, is still available in any quantity.

Executives at Disney Home Video refused to comment on their policies, but Tania Steele, a spokeswoman for the parent company, Buena Vista Home Video, said that, "Once a Disney animated classic is put back into the vaults, that's it. We release an animated classic, then it goes on the market for a limited time only, then it goes back into the vault."

When asked if such titles will ever be brought back, Steele said only, "There is no future date, no future plans to release them again."VIDEO QUESTION

Q: I read that VCRs in Japan can record a program and automatically cut out commercials. Is this true? Will they be sold in the United States?

A: Last year, Mitsubishi introduced a VCR in Japan that can omit commercials during recordings, but it wouldn't work here. It detected the change from bilingual programs (in stereo) to single-language ads (in mono), and ceased recording. Predictably, advertisers were very disturbed. - Andy Wickstrom (Knight-Ridder)