From the video, i'm going to tell you what i would have done after experimenting a lot with Roy in past.
I would like you to try these out for yourself, to see if it helps or not. I'm not a Roy, main but i find his special attack highly unrated.
1 - Use Flare Blade More
Flare Blade is an Complete under used attack which can be used in a lot of tight, and loose spots.
One example of this is aerial attack. Roy's Aerial attack are weak, the only one of any real use is N-air.
So try replace any other aerial attack, other then N-air with Flare Blade, yes B-air included, since it's possible to turn around, and hit with it while in mid air.
Flare Blade is also faster then F-Smash, for those who weave in and out of your f-smash, Flare blade will like catch them.
Also your edge guarding with Flare Blade is off, When edge guarding with Flare Blade the Closer they are to the edge, the farther you should be. The farther they are from the edge, the closer you should be.
The Flare Blade has 5 charge settings, and are visual possible to see the steps by watching the colors, and the flashes Roy changes. The 3 Charge is equal to a full charge f-smash, the the 4, and 5 being stronger.
When to use DED?
You Didn't use DED at all, and killed yourself when you did.
The DED should be used in very optional placing, for example DED, could be used in place of Dash Attack. DED has to be used very quickly so to no let them recover from the first attack of the DED, after the first attack you have choose which to follow with. Depending on the wieght, and falling speed of the character you should choose wither to hit them up, or across.
I find that you should hit up with heavy characters, and across with light. After the first two steps, you now should have them position to complete your combo. But now you have the third step, this step is an trap for both players. Roy has 3 options here, 1 - Finish the Combo, 2 - Toss them into the air, and 3 - Knock them away. Option 1 is the hardest to do, and option 2 and 3 are more safer. Because if you miss, your left open for punishment during step 4.
DED can be use in many ways, including edge guarding to look fancy.
Reading for an counter?
You only used counter 1 time.
There a lot of time you could have counter, but you either Shield, tried to grab, or attack. Roy counter is better the marth's, and should be put into practice to learn to predict an attack.
Stay on the ground
Roy is best when his feet are on the ground, don't chase someone when they're in the air unless you put the there. There are no attacks that shoot directly down from the air that has the knock back to kill you.
