Problem 1: Birthday Candy: https://youtu.be/y3vnhJ2rrd0
Problem 2: SixteenQueens: https://youtu.be/Ky95auI5p5o
Problem 3: ResistorFactory: coming ...

Problem A: Vasya and Password: https://youtu.be/5ZdRBNJXHjg
Problem B: Relatively Prime Pairs: https://youtu.be/vcF8mTjgt6o
Problem C: Vasya and Multisets: https://youtu.be/q56uTA6t9Uk?t=3m8s
Problem D: Bicolorings: https://youtu.be/lSyQQ1T6iQ8

Educational Codeforces Round 51 (Rated for Div. 2)
1051A - Vasya And Password
1051B - Relatively Prime Pairs
1051C - Vasya and Multisets
1051D - Bicolorings

Problem 1: BinaryCalculator: https://youtu.be/dG6RdmnJSuw
Problem 2: TeleportationMaze: https://youtu.be/z1F0UNl2mwQ
Problem 3: coming

Problem 1: MinimizeAbsoluteDifferenceDiv2: https://youtu.be/ApEOvRWdZ7I
Problem 2: BuildingSpanningTreesDiv2: https://youtu.be/SXhYlF2sdUk
Problem 3: HamiltonianPathsInGraph: https://youtu.be/_eD3HE4piYs

Problem 1: DeckOfCards: https://youtu.be/nggxQeCUbtw
Problem 2: CubeStackingGame: https://youtu.be/3EUxow6Ysw8
Problem 3: TheFlippingGame2: https://youtu.be/OuiEk87IVQs

Links:

Problem A — Friends Meeting: https://youtu.be/bFEmX3y8idE
Problem B — World Cup: https://youtu.be/tzF_nagpR5A
Problem C — Laboratory Work: https://youtu.be/hEsuRDgmo_8
Problem D — Peculiar Apple-Tree: https://youtu.be/aqVF3vpiERE

Site Links:
Codeforces Round 468 (Div. 2, based on Technocup 2018 Final Round)
931A - Friends Meeting
931B - World Cup
931C - Laboratory Work
931D - Peculiar apple-tree